This page in your language

فارسی

العربية

Deutsch

Español

Français

日本語

한국어

Português

中文

हिन्दी

A2 verb 9 min read

失くす

nakusu

Practice it Examples Notes & Tips 失くす in 30 Seconds

Explanation 失くす in your Level:

At the A1 level, learners focus on the most basic application of 失くす (usually written as なくす). This involves identifying the word as a way to say you don't have something anymore because you lost it. The focus is on simple sentences involving everyday objects like かぎ (keys), さいふ (wallet), or ぺん (pen). Grammatically, A1 learners use the dictionary form or the polite past form なくしました. The key goal at this level is simply to communicate the fact of the loss to someone else, such as a teacher or a clerk, without worrying too much about complex nuances or the transitive/intransitive distinction. Examples: 「かぎをなくしました」 (I lost my keys).

At the A2 level, learners begin to use 失くす in more varied sentence structures. You will learn to use the 〜てしまう form (失くしてしまいました) to express regret or the accidental nature of the loss, which is much more natural in Japanese. You also start to use the negative form 失くさない in requests like 「失くさないでください」 (Please don't lose it). At this stage, you should be able to provide a brief context for the loss, such as where it happened (「電車で...」) or when (「昨日...」). The distinction between 失くす (I lost it) and なくなる (It is gone) becomes important for clarity in basic conversations.

By B1, you should be comfortable using 失くす for both physical objects and abstract concepts like 自信 (confidence) or やる気 (motivation). You will use the verb in complex sentences, such as 「自信を失くさないように、毎日練習します」 (I practice every day so as not to lose confidence). You also start to recognize the difference between 失くす and more formal words like 紛失する. Learners at this level can use the potential form 失くせる in hypothetical scenarios and understand the causative form 失くさせる (to make someone lose something). You can also discuss the consequences of losing something, using conditional forms like 〜たら or 〜ば.

At the B2 level, the focus shifts to the nuance and register of 失くす. You understand that 失くす is slightly less formal than 失う (ushinau) and can choose between them based on the gravity of the situation. You might use 失くす in social contexts to describe 'losing face' or 'losing interest' in a hobby. You are proficient in using the passive form 失くされる to describe when someone else's actions caused your loss, and you can use the verb in relative clauses effectively. You also begin to understand the etymological roots and how the kanji 失 functions in other compound words, helping you guess the meaning of related vocabulary.

C1 learners use 失くす with precision and stylistic flair. You can use it in literary or academic contexts to describe the loss of cultural heritage or the disappearance of a specific species (though more formal terms are common, 失くす can be used for stylistic impact). You understand the subtle differences in tone when using the kanji vs. hiragana. You can engage in deep discussions about the psychological impact of loss and use 失くす in idiomatic expressions effortlessly. Your ability to switch between 失くす, 失う, 紛失する, and 欠如する (kejyosuru - to lack) based on the specific context is a hallmark of this level.

At the C2 level, 失くす is part of a vast and nuanced vocabulary. You can use it to critique literature, discuss philosophical concepts of 'nothingness,' or analyze sociolinguistic shifts in how the word is used across different generations. You are aware of rare dialectal variations and the historical evolution of the word from Old Japanese. You can use 失くす in highly sophisticated wordplay or poetry, where the choice of this specific verb carries specific emotional weight or alliteration. At this stage, the word is not just a tool for communication, but a brush with which you can paint complex, subtle meanings in any register.

Practice it Examples Notes & Tips

失くす in 30 Seconds

Used for losing physical items like keys, wallets, or phones in daily life.
Extends to losing internal states like confidence, motivation, or interest.
A transitive verb (requires 'o' particle) implying the person is the agent.
Commonly used with '~te shimau' to express regret or accidental loss.

The Japanese verb 失くす (nakusu) is a fundamental transitive verb primarily meaning 'to lose' an object or a physical thing. At its core, it describes the action where a person misplaces something or causes it to go missing through some level of personal involvement or oversight. While it is frequently written in hiragana as なくす, the kanji 失 (loss/error) provides a visual anchor for the concept of something being gone. Understanding 失くす requires distinguishing it from its intransitive counterpart, なくなる (nakunaru), which simply means 'to be lost' or 'to disappear' without focusing on who did it.

Core Usage: Used when you personally misplace a physical item like keys, a wallet, or a phone. It implies a transition from possession to non-possession due to an action or lack of care.

昨日、公園で鍵を失くしてしまいました。
(Yesterday, I accidentally lost my keys at the park.)

In a broader sense, 失くす can also extend to abstract concepts such as 'losing confidence' (自信を失くす) or 'losing one's appetite' (食欲を失くす). However, for very formal or heavy emotional losses—like losing a life or a significant opportunity—the word 失う (ushinau) is often preferred. 失くす remains the 'everyday' word for the common frustrations of daily life. It is a Godan verb, meaning it follows the standard 'u' to 'i' conjugation pattern for the polite form (なくします).

Grammatical Role: It is a transitive verb (他動詞, tadoushi), meaning it takes a direct object marked by the particle を (o). You are the agent of the loss.

Culturally, losing something in Japan often triggers a specific set of social responses. If you lose something in a public space, there is a high probability of finding it at a 'Koban' (police box). When reporting this, you would say 「〜を失くしました」. This word communicates not just the fact of the loss, but often an implicit apology for one's own carelessness, reflecting the Japanese value of self-responsibility for personal belongings.

財布を失くすと、本当に困りますよね。
(Losing a wallet is really troublesome, isn't it?)

Social Nuance: Using 失くす suggests a personal failing or accident. It is less formal than 紛失する (funshitsu suru), which is used in official documents or business announcements.

In summary, 失くす is your go-to verb for the physical disappearance of items you own. It covers everything from the mundane (losing a pen) to the stressful (losing a passport). Its usage peaks in daily conversations, anecdotes about travel mishaps, and expressions of psychological states where a positive attribute (like motivation) has vanished due to external pressure or internal doubt.

Using 失くす (nakusu) correctly involves understanding its transitive nature and its common pairings with the 〜てしまう grammar structure. Because losing something is usually an accidental and regrettable action, Japanese speakers rarely use the simple past 失くした (nakushita) in isolation when speaking about themselves; instead, they opt for 失くしてしまった (nakushite shimatta) to convey that 'oops' feeling.

The Basic Structure: [Owner] + は + [Object] + を + 失くす. This is the standard way to state who lost what.

弟はよく傘を失くします。
(My younger brother often loses his umbrella.)

When discussing abstract concepts, the structure remains the same, but the nuance shifts. For example, 'to lose interest' is 興味を失くす (kyoumi o nakusu). In these cases, the verb suggests a gradual or sudden fading of a feeling. It’s important to note that while 失くす is common for 'losing confidence' (自信を失くす), for 'losing a life' or 'losing a job,' speakers often shift to the more formal 失う (ushinau) to respect the gravity of the situation.

Potential Form: The potential form is 失くせる (nakuseru), though it is rarely used because people don't usually 'can lose' things intentionally. You might hear it in negative hypothetical contexts: 'I can't afford to lose this.'

大事な書類だから、絶対に失くさないでください。
(This is an important document, so please definitely do not lose it.)

Another key use case is the causative-passive or passive forms, though they are less common for this specific verb. If you want to say something was lost by someone else, you might use the passive 失くされる (nakusareru), but more naturally, you would use the intransitive なくなる (nakunaru) to describe the state of the object being gone.

Common Pairings: - 鍵を失くす (lose keys)
- 自信を失くす (lose confidence)
- やる気を失くす (lose motivation)

テストの点数が悪くて、自信を失くしてしまいました。
(My test scores were bad, and I've lost my confidence.)

Finally, remember that 失くす is often used in the negative imperative to give advice or warnings. 'Don't lose it!' is a very common phrase in parenting or when lending someone an item. Using 〜ないように (so as not to) with 失くす is also a very natural A2/B1 level construction.

You will encounter 失くす (nakusu) in a variety of real-life settings, ranging from the mundane to the slightly dramatic. Because it deals with the universal human experience of misplacing things, it is a staple of spoken Japanese. If you spend time in Japan, you are almost guaranteed to hear this word in public announcements, service encounters, and social venting.

At the Police Box (Koban): This is the most common place for learners to use the word. When you go to report a missing item, you tell the officer, 「〜を失くしたのですが...」 (I lost my..., but...). They will then ask where and when you lost it.

すみません、この近くで切符を失くしてしまいました。
(Excuse me, I accidentally lost my ticket near here.)

In schools and workplaces, you'll hear it when people are looking for shared supplies or when someone is explaining why they don't have a required document. In these environments, it's often accompanied by an apology (申し訳ありません). Teachers might warn students: 「プリントを失くさないように！」 (Don't lose your handouts!).

In Anime and Dramas: Characters often use 失くす to describe losing something sentimental, like a charm or a letter. It’s a common trope to trigger a search scene or a moment of vulnerability. You might also hear it in a metaphorical sense, like 'losing one's way' or 'losing one's heart' (though 失う is more common for the latter).

彼女は大切なペンダントを失くして、泣いています。
(She lost her precious pendant and is crying.)

In casual conversations with friends, 失くす is often the start of a story. 'You won't believe it, I lost my phone again!' (またスマホ失くしちゃった！). It serves as a conversational hook to discuss the troubles of the day. It is also used in self-deprecating humor about being clumsy or forgetful.

Customer Service: If you lose a membership card, the staff might say: 「カードを紛失された場合は...」 (In the case that you have lost your card...). Note that they use the formal 紛失 (funshitsu) instead of 失くす to maintain professional distance and politeness.

やる気を失くした時は、ゆっくり休むのが一番です。
(When you've lost your motivation, resting well is the best thing.)

Learning 失くす (nakusu) often involves navigating a few linguistic 'traps' where English logic doesn't quite match Japanese usage. The most frequent errors involve confusing it with other verbs that translate as 'lose' in English, or mixing up transitive and intransitive forms.

Mistake 1: Using 'Nakusu' for Games/Competitions: In English, we say 'I lost the game.' In Japanese, you cannot say 「試合を失くした」. For competitions, you must use 負ける (makeru). 失くす is strictly for physical objects or specific psychological states.

Correct: 試合に負けました。(I lost the match.)
Incorrect: 試合を失くしました。

The second major mistake is the confusion between 失くす (nakusu) and 失う (ushinau). While they share a kanji, 失う is for 'big' things: losing a loved one, losing a job, losing trust, or losing a limb. Using 失くす for a tragic death sounds oddly casual and inappropriate. Conversely, using 失う for a lost eraser sounds overly dramatic, like you've suffered a life-altering tragedy over stationery.

Mistake 2: Nakusu vs. Nakunaru: Remember the particle rule. 失くす takes を (o) because it's transitive. なくなる takes が (ga) because it's intransitive. Saying 「鍵が失くした」 is grammatically incorrect; it should be 「鍵を失くした」 (I lost the keys) or 「鍵がなくなった」 (The keys are gone).

Correct: お金を失くした。(I lost the money.)
Correct: お金がなくなった。(The money is gone.)

Another nuance involves the word 落とす (otosu - to drop). If you lose your wallet by dropping it on the street, you can use either 落とす or 失くす. However, if you simply can't find it in your house, 失くす is the only choice. Don't use 落とす unless you actually think it fell out of your pocket or bag.

Mistake 3: Forgetting 'Shimau': While not a 'mistake' in the strict sense, failing to use 〜てしまう (te shimau) after 失くす can make you sound a bit robotic or indifferent. Since losing things is usually bad, Japanese speakers expect to hear that emotional 'regret' marker.

Better: パスポートを失くしてしまいました。
(I have unfortunately lost my passport.)

To truly master 失くす (nakusu), you must understand how it fits into the ecosystem of other Japanese words meaning 'to lose,' 'to disappear,' or 'to misplace.' Choosing the right one depends on the object, the importance, and the cause of the loss.

失くす (nakusu) vs. 失う (ushinau): Nakusu: Casual, physical objects (keys, wallet), or temporary feelings (confidence).
Ushinau: Formal, significant/permanent things (life, opportunity, trust, history).

彼は事故で視力を失いました。
(He lost his eyesight in an accident. - Uses 'ushinau' for something permanent and tragic.)

Another frequent point of comparison is 落とす (otosu). While 失くす describes the general state of not having the item anymore, 落とす specifically identifies the physical act of dropping it. If you say 「財布を落としました」, it implies you know how you lost it. If you say 「財布を失くしました」, you are just saying it's gone and you don't know where it is.

失くす (nakusu) vs. 紛失する (funshitsu suru): Nakusu: Used in conversation and daily life.
Funshitsu suru: Sino-Japanese compound used in official reports, legal terms, or business emails. 'The library books were lost' in a notice would use 紛失.

会員証を紛失した場合は、再発行が必要です。
(If you lose your membership card, re-issuance is necessary. - Formal usage.)

Lastly, consider the difference between 失くす and 負ける (makeru). This is the most common error for English speakers. English uses 'lose' for both objects and games. Japanese strictly separates them. You 'lose' your keys (失くす) but you 'lose' the tennis match (負ける).

Summary Table: - Physical item: 失くす
- Dropped item: 落とす
- Left behind: 置き忘れる
- Game/Match: 負ける
- Serious/Abstract: 失う

試合に負けて、やる気を失くしました。
(I lost the match and lost my motivation. - Shows both verbs in one context.)

How Formal Is It?

Fun Fact

In ancient Japanese, the concept of 'loss' was often tied to spirits or 'kamikakushi' (being hidden by gods) if an object couldn't be found.

Pronunciation Guide

UK /na.ku.su/

US /nɑ.ku.su/

Heiban (Flat) pitch accent in standard Tokyo Japanese, meaning the pitch stays relatively level after an initial rise.

Rhymes With

Kasu (to lend) Dasu (to put out) Tasu (to add) Nasus (to do) Husu (to lie down) Musu (to steam) Sasu (to point) Hasu (lotus)

Common Errors

Pronouncing 'u' too strongly (it should be almost whispered).
Confusing with 'nagasu' (to let flow).
Failing to distinguish from 'nakunaru' (intransitive).
Stress on the wrong syllable.
Vowel lengthening (it's 'nakusu', not 'naakusu').

Difficulty Rating

Reading 2/5

The kanji is simple, but often written in hiragana.

Writing 3/5

Remembering the stroke order for 失 is important.

Speaking 2/5

Easy to pronounce, but requires correct particle usage.

Listening 2/5

Distinct sound, but don't confuse with 'nakunaru'.

What to Learn Next

Prerequisites

ない (nai) ある (aru) もの (mono) かぎ (kagi) さいふ (saifu)

Learn Next

なくなる (nakunaru) 失う (ushinau) 落とす (otosu) 見つける (mitsukeru) 探す (sagasu)

Advanced

紛失 (funshitsu) 喪失 (soushitsu) 遺失 (ishitsu) 欠如 (kejyo)

Grammar to Know

Transitive vs. Intransitive (他動詞と自動詞)

鍵を失くす (Transitive) vs. 鍵がなくなる (Intransitive)

~te shimau (Regret/Completion)

大切なペンを失くしてしまいました。

~nai you ni (So as not to)

失くさないようにカバンに入れました。

~nai de kudasai (Negative Request)

絶対に失くさないでください。

Relative Clauses with Past Tense

昨日失くした財布が見つかりました。

Examples by Level

かぎをなくしました。

I lost my keys.

Basic polite past tense.

ペンをなくさないでください。

Please do not lose the pen.

Negative request form: ~nai de kudasai.

どこでなくしましたか？

Where did you lose it?

Interrogative sentence with 'doko' (where).

昨日、さいふをなくしました。

Yesterday, I lost my wallet.

Time marker 'kinou' used with past tense.

大切な本をなくしました。

I lost an important book.

Adjective 'taisetsu na' modifying the object.

消しゴムをなくした。

I lost my eraser.

Casual past tense.

おもちゃをなくさない！

Don't lose your toy!

Casual negative imperative.

スマホをなくして、困っています。

I lost my smartphone and I'm in trouble.

Te-form used to connect two clauses.

切符を失くしてしまいました。

I accidentally lost my ticket.

~te shimau expresses regret.

失くさないように、カバンに入れましょう。

Let's put it in the bag so as not to lose it.

~nai you ni (so as not to).

なくした物は、何ですか？

What is the thing you lost?

Relative clause: nakushita mono (the thing that was lost).

彼はよく傘を失くします。

He often loses his umbrella.

Adverb 'yoku' (often) used with habitual action.

テストで自信を失くしました。

I lost confidence because of the test.

Abstract object 'jishin' (confidence).

なくしちゃった、どうしよう！

I lost it, what should I do!

Casual contraction of ~te shimatta.

公園で帽子を失くしたかもしれません。

I might have lost my hat at the park.

~kamoshiremasen (might).

失くさないために、名前を書きます。

In order not to lose it, I will write my name.

~nai tame ni (in order not to).

やる気を失くすようなことは言わないで。

Don't say things that make me lose motivation.

Relative clause modifying 'koto' (thing/matter).

一度失くした信用を取り戻すのは難しい。

It is difficult to regain trust once lost.

Abstract object 'shinyou' (trust/credit).

パスポートを失くした時の手続きを教えてください。

Please tell me the procedure for when one loses their passport.

~toki (when/the time that).

そんなに簡単に自信を失くさないでください。

Please don't lose your confidence so easily.

Adverbial phrase 'sonna ni kantan ni'.

失くしたと思っていた鍵が、ポケットから出てきた。

The keys I thought I had lost turned up in my pocket.

~to omotte ita (thought that...).

彼はギャンブルでお金をすべて失くした。

He lost all his money through gambling.

Emphasizing the extent with 'subete'.

もし明日携帯を失くしたら、どう連絡すればいい？

If I lose my phone tomorrow, how should I contact you?

Conditional ~tara.

失くしたくない思い出がたくさんあります。

There are many memories I don't want to lose.

Desire form ~tai (nakushitai) in negative.

不祥事によって、その会社は社会的信用を失くした。

Due to the scandal, that company lost its social credibility.

Cause-effect relationship using 'ni yotte'.

彼は怒りのあまり、理性を失くしてしまった。

He lost his reason out of sheer anger.

~no amari (so much that...).

伝統的な文化を失くさないための活動が行われている。

Activities are being carried out to not lose traditional culture.

Passive voice 'okonawarete iru'.

君に失くされたら困るから、私が預かっておくよ。

I'll keep it for you because it'll be a problem if you lose it.

Passive form 'nakusareru' to show inconvenience.

興味を失くした本を、古本屋に売った。

I sold the books I lost interest in to a used bookstore.

Relative clause with 'kyoumi o nakushita'.

一度失くしたチャンスは二度と戻ってこない。

A chance once lost will never come back again.

Emphasis with 'nido to...nai'.

失くし物を探す専門のサービスがあるらしい。

Apparently, there's a service specialized in finding lost items.

Noun form 'nakushimono' (lost item).

彼女は悲しみのどん底で、生きる希望を失くしかけていた。

In the depths of sadness, she was on the verge of losing hope to live.

~kakete ita (was on the verge of).

現代社会において、人間関係の希薄さが心の余裕を失くさせている。

In modern society, the thinness of human relationships is causing people to lose their peace of mind.

Causative form 'nakusasete iru'.

その政策は、結果的に地方の活力を失くすことになった。

That policy resulted in losing the vitality of the rural areas.

~koto ni natta (it turned out that...).

美意識を失くした建築物が街並みを破壊している。

Buildings that have lost their sense of aesthetics are destroying the cityscape.

Abstract noun 'biishiki' (aesthetic sense).

彼がこれほどまでに自信を失くした原因は不明だ。

The reason why he lost his confidence to this extent is unknown.

Koto-clause used as a subject.

一度失くした名声を取り戻すには、並大抵の努力では足りない。

To regain fame once lost, ordinary effort is not enough.

Conditional 'ni wa' with 'tarinai'.

失くして初めて、その物の本当の価値に気づくことが多い。

It is often only after losing something that we realize its true value.

~te hajimete (only after...).

デジタルの普及が、手書きの文化を失くしつつある。

The spread of digital technology is gradually losing the culture of handwriting.

~tsutsu aru (is in the process of).

彼はプライドを失くしてまで、その仕事にしがみついた。

He clung to that job even to the point of losing his pride.

~made (even to the extent of).

言葉を失くすほどの絶景が、目の前に広がっていた。

A landscape so breathtaking it made me lose my words spread out before me.

Idiomatic use: 'kotoba o nakusu' (to be speechless).

自己を失くすことなく、集団の中で調和を保つのは至難の業だ。

Maintaining harmony within a group without losing one's self is an extremely difficult task.

Negative 'koto naku' (without doing...).

その詩人は、失くした愛への鎮魂歌を詠み続けた。

The poet continued to compose requiems for a lost love.

Literary context.

文明の進歩は、我々から野生の直感を失くさせたのだろうか。

Has the progress of civilization caused us to lose our wild intuition?

Philosophical question.

権力争いの中で、彼は次第に人間性を失くしていった。

In the struggle for power, he gradually lost his humanity.

Gradual change with ~te iku.

失くした過去は、記憶の断片の中にしか存在しない。

The lost past exists only within the fragments of memory.

Metaphorical usage.

彼はすべてを失くした後に、ようやく真実の自由を見出した。

After losing everything, he finally discovered true freedom.

Spiritual/Existential context.

情報の洪水が、思索の時間を我々から失くしている。

The flood of information is depriving us of time for contemplation.

Abstract transitive usage.

Common Collocations

鍵を失くす

自信を失くす

やる気を失くす

財布を失くす

興味を失くす

食欲を失くす

言葉を失くす

信用を失くす

場所を失くす

希望を失くす

Common Phrases

失くし物

— A lost item or the act of losing things.

失くし物を探しています。

失くしちゃった

— Casual 'I lost it' (with regret).

あ、消しゴム失くしちゃった。

失くさないように

— So as not to lose it.

失くさないように気をつけて。

失くしたと思っていた

— Thought I had lost it (but maybe found it).

失くしたと思っていたペンが出てきた。

もう失くさないで

— Don't lose it again.

次はもう失くさないでね。

失くすのが怖い

— Afraid of losing (something).

これを失くすのが怖いです。

自信を失くしそう

— Likely to lose confidence.

難しすぎて自信を失くしそう。

失くして困る

— To be in trouble because of losing something.

スマホを失くして困っている。

失くすわけにはいかない

— Cannot afford to lose.

このチャンスを失くすわけにはいかない。

失くした場所

— The place where something was lost.

失くした場所に心当たりはありますか？

Often Confused With

失くす vs 負ける (makeru)

Used for losing a game or match. Never use 'nakusu' for competitions.

失くす vs 失う (ushinau)

Used for serious, permanent, or very formal losses (life, job, trust).

失くす vs なくなる (nakunaru)

The intransitive version; used when something is gone, but the agent is not the focus.

Idioms & Expressions

"言葉を失くす"

— To be speechless (due to shock, beauty, or surprise).

その悲報に、誰もが言葉を失くした。

General

"自信を失くす"

— To lose self-confidence.

一度の失敗で自信を失くす必要はない。

General

"やる気を失くす"

— To lose motivation or the will to do something.

雨が降ってきたので、出かけるやる気を失くした。

Casual

"興味を失くす"

— To lose interest in something.

彼はその研究にすっかり興味を失くしてしまった。

General

"食欲を失くす"

— To lose one's appetite.

嫌なニュースを見て食欲を失くした。

General

"居場所を失くす"

— To feel like one doesn't belong or has no place.

会社での居場所を失くしてしまった。

Social

"面目を失くす"

— To lose face or honor.

大失敗をして、上司の前で面目を失くした。

Formal

"影を失くす"

— To lose one's presence or become obscure.

かつてのスターも、今では影を失くしている。

Literary

"正気を失くす"

— To lose one's sanity or senses (usually 'ushinau' is more common, but 'nakusu' is used colloquially).

あまりのショックに正気を失くしそうだった。

Dramatic

"希望を失くす"

— To lose hope.

彼は絶望して希望を失くしてしまった。

General

Easily Confused

失くす vs 落とす (otosu)

Both result in an item being gone.

'Otosu' is specifically dropping it; 'nakusu' is the general state of loss.

道を歩いていて財布を落とした。

失くす vs 忘れる (wasureru)

Forgetting an item often leads to losing it.

'Wasureru' is the mental act of forgetting; 'nakusu' is the physical fact of the loss.

傘を電車に忘れた。

失くす vs 亡くなる (nakunaru)

Sounds identical to the intransitive 'nakunaru' (to be lost).

'亡くなる' specifically means 'to pass away' (die).

祖父が亡くなりました。

失くす vs 無くす (nakusu)

Same reading, different kanji.

'無' is often used for abstract things (making something non-existent), while '失' is for losing possession.

差別を無くす (Eliminate discrimination).

失くす vs 減らす (herasu)

Both involve something decreasing or going away.

'Herasu' is 'to reduce' the amount; 'nakusu' is 'to lose' the item entirely.

体重を減らす。

Sentence Patterns

[Object] をなくしました。

ペンをなくしました。

[Object] を失くしてしまいました。

かぎを失くしてしまいました。

[Object] を失くさないでください。

傘を失くさないでください。

[Object] を失くさないように [Action]。

失くさないように名前を書きます。

自信を失くした時、[Action]。

自信を失くした時、音楽を聴きます。

[Reason] で [Object] を失くす。

不注意で信用を失くした。

[Object] を失くしつつある。

伝統が失くしつつある。

[Object] を失くすことなく [Action]。

自分を失くすことなく生きたい。

Word Family

Nouns

失くし物 (nakushimono - lost item)

紛失 (funshitsu - loss)

喪失 (soushitsu - loss/deprivation)

Verbs

なくなる (nakunaru - to be lost/intransitive)

失う (ushinau - to lose/formal)

見失う (miushinau - to lose sight of)

Adjectives

失礼 (shitsurei - rude/loss of etiquette)

失望した (shitsubou shita - disappointed)

失敗 (shippai - failure)

失業 (shitsugyou - unemployment)

失恋 (shitsuren - broken heart)

失望 (shitsubou - despair)

失神 (shisshin - fainting)

How to Use It

frequency

Very frequent in daily spoken Japanese.

Common Mistakes

試合を失くした (Shiai o nakushita) → 試合に負けた (Shiai ni maketa)
You cannot use 'nakusu' for losing games or matches.
鍵が失くした (Kagi ga nakushita) → 鍵を失くした (Kagi o nakushita)
'Nakusu' is transitive and requires the 'o' particle.
道を失くした (Michi o nakushita) → 道に迷った (Michi ni mayotta)
'To lose one's way' is a different idiom in Japanese.
おじいさんを失くした (Ojiisan o nakushita) → おじいさんを亡くした/失った
'Nakusu' (失くす) is too casual for the death of a person.
ペンを落として失くした (Pen o otoshite nakushita) → ペンを失くした / ペンを落とした
While not strictly wrong, it's redundant. Choose one based on the focus.

Tips

Particle Choice

Always use 'o' with 'nakusu'. If you use 'ga', you must change the verb to 'nakunaru'.

The Koban

If you 'nakusu' something in Japan, go to the nearest Koban (police box). They are very helpful!

Abstract Feelings

Use 'nakusu' for 'confidence' and 'motivation' when they disappear because of an event.

Pitch Accent

Keep it flat. Don't stress any particular syllable too much.

Regret Marker

Use '~te shimau' when you feel bad about losing the item. It sounds much more natural.

Kanji vs Hiragana

Use kanji (失くす) for physical objects in formal writing; hiragana (なくす) for abstract feelings.

Trains

If you leave something on a train, it's usually called 'wasuremono' (forgotten item), not 'nakushimono'.

No-Ku-Su

Remember: No-Keys-Lost = Nakusu.

Apologizing

When you lose someone else's item, apologize profusely before saying you lost it.

Business

In business emails, use 'funshitsu' (紛失) instead of 'nakusu' for lost documents.

Memorize It

Mnemonic

Think of 'No Keys' -> 'Na-Ku-Su'. When you have 'no keys,' you have 'nakusu'ed them.

Visual Association

Imagine a person looking at their empty hand where a set of keys used to be, with a thought bubble showing the keys flying away.

Word Web

鍵 (key) 財布 (wallet) 自信 (confidence) 探す (search) 警察 (police) 忘れる (forget) 落とす (drop) 見つける (find)

Challenge

Try to list five things you have lost in the last year using the sentence pattern '[Item] o nakushimashita.'

Word Origin

Derived from the adjective 'nai' (not/non-existent) combined with the verbalizing suffix 'su' (to do/make). This literally means 'to make something non-existent.'

Original meaning: To cause something that was there to be gone.

Japonic / Old Japanese.

Cultural Context

Be careful using 'nakusu' for people. While 'nakunaru' is a polite way to say someone died, 'nakusu' is rarely used for people unless in very specific poetic contexts. Use 'ushinau' for the death of a loved one.

English speakers often use 'lose' for games, but must remember to use 'makeru' in Japanese.

The movie 'Dare mo Shiranai' (Nobody Knows) features themes of loss. Haruki Murakami often writes about characters who 'nakusu' their identity or sense of self. The concept of 'Mottainai' (what a waste) is often triggered when someone 'nakusu' a useful object.

Practice in Real Life

Real-World Contexts

At the Police Box

〜を失くしました。
どこで失くしたか分かりません。
失くし物の届を出したいです。
見つかったら連絡してください。

At School/Work

宿題を失くしてしまいました。
やる気を失くしました。
大切な書類を失くさないでください。
消しゴムを失くしたので貸してください。

Traveling

パスポートを失くしました！
切符を失くすと困ります。
荷物を失くさないように気をつけて。
ホテルの鍵を失くしました。

Daily Chores

靴下を片方失くした。
リモコンを失くしたみたいだ。
コンタクトレンズを失くした。
レシートを失くさないで。

Emotional/Mental State

自信を失くしています。
彼への興味を失くした。
食欲を失くすほど暑い。
希望を失くさないで。

Conversation Starters

"最近、何か失くしたものはありますか？ (Have you lost anything recently?)"

"大切なものを失くした時、どうしますか？ (What do you do when you lose something important?)"

"今までで一番困った失くし物は何ですか？ (What is the most troublesome thing you've ever lost?)"

"どうすれば物を失くさないようになると思いますか？ (How do you think one can stop losing things?)"

"日本で失くし物をしたことがありますか？ (Have you ever lost something in Japan?)"

Journal Prompts

今日、何かを失くして困ったこと、または失くさないように気をつけたことを書いてください。 (Write about something you lost today or how you were careful not to lose something.)

「自信を失くした時」にどうやって立ち直るか、自分の経験を書いてください。 (Write about your experience of how you recover when you lose confidence.)

もし全財産を失くしたら、まず何をしますか？ (If you lost all your assets, what would you do first?)

子供の頃に失くして、今でも覚えている大切なものについて書いてください。 (Write about something important you lost as a child that you still remember.)

「失くす」と「見つける」のどちらが人生において重要だと思いますか？ (Which do you think is more important in life: 'losing' or 'finding'?)

Frequently Asked Questions

10 questions

No, you must use 'makeru'. 'Nakusu' is only for objects or feelings.

'Nakusu' is for daily items (keys, etc.). 'Ushinau' is for serious things (lives, jobs).

Yes, it is very common to write it as 'なくす', especially in casual contexts or for abstract feelings.

Use 'michi ni mayou' (道に迷う), not 'nakusu'.

Always use the object particle 'を' (o) for the thing you lost.

No. 'Nakunaru' (intransitive) can mean someone died, but 'nakusu' (transitive) does not.

No, it's a standard, everyday word for misplacing things.

Yes, 'shokuyoku o nakusu' is a very common expression.

'Otosu' means you dropped it. 'Nakusu' just means it's gone.

Say '[Item] o nakushimashita' or '[Item] o wasuremashita'.