Grammar Rule in 30 Seconds
Use 'nighttime' (one word) for American English and 'night-time' (hyphenated) for British English; avoid using two separate words.
- American English prefers the closed compound 'nighttime' for both nouns and adjectives.
- British English traditionally uses the hyphenated 'night-time', though 'nighttime' is becoming more common.
- Avoid 'night time' as two separate words in formal writing, as it is generally considered incorrect.
Overview
nighttime と night-time も、まさにその代表例です。一見すると、ハイフン一つがあるかないかという非常に小さな違いですが、実はこの背後には英語の歴史的な進化や、地域によるスタイルの違いが隠されています。nighttime と night-time は、どちらも文法的に正しく、意味も全く同じです。どちらも「日没から日の出までの暗い時間」、つまり日本語で言うところの「夜間」や「夜の時間」を指します。間違いを恐れる必要はありませんが、この二つの使い分けを知ることは、皆さんの英語をより「自然で、洗練されたもの」にするための大きなステップになります。nighttime: ハイフンのない一単語（closed compound）の形式で、主にアメリカ英語で標準的に使われます。現代的で、デジタルのコミュニケーションやグローバルなビジネスシーンではこちらが主流になりつつあります。night-time: ハイフンで繋いだ形式（hyphenated compound）で、伝統的なイギリス英語でよく見られます。保守的でフォーマルな印象を与えるスタイルです。
night time）」から始まり、頻繁に使われるうちに「ハイフンで繋がれた形（night-time）」になり、最終的に「完全に一単語（nighttime）」へと進化していく傾向があります。現在、この言葉はその進化の過程にあるため、複数の形が共存しているのです。この記事では、日本人学習者が特につまずきやすい「名詞句としての night time（二単語）」との違いも含め、詳しく解説していきます。nighttime および night-time は、文法的に二つの役割を果たします。- American style:
The city looks beautiful during the nighttime.
- British style:
The city looks beautiful during the night-time.
nighttime 全体が一つの名詞として扱われています。日本語で「夜間は〜」と言うのと感覚は同じです。nighttime または night-time）として示すことが推奨されます。- American style:
I have a specific nighttime routine.
- British style:
I have a specific night-time routine.
nighttime は routine を修飾しています。もしこれを night time routine と三つの単語で書いてしまうと、どこからどこまでが一つの概念なのかが曖昧になり、読み手に「不自然な英語」という印象を与えてしまいます。nighttime という一つの形容詞的な単語にまとめることで、スムーズに次の名詞へ繋げることができます。この「助詞なしで名詞を修飾する感覚」を掴むことが、中級レベル（B1）から上級へとステップアップする鍵となります。nighttime | 1単語 | 連結複合語 | 名詞・形容詞 | アメリカ英語 | Nighttime safety is important.|
night-time | ハイフンあり | ハイフン複合語 | 名詞・形容詞 | イギリス英語 | The night-time economy is growing.|
night time | 2単語 | 名詞句 | 特定の「時間」を指す名詞 | 共通（限定的） | What night time is the meeting?|
nighttime と night-time は「夜という概念や期間」を指す際に、地域によって使い分けられているだけです。しかし、一番下の night time（二単語）だけは、使い方が全く異なります。daytime との興味深い違いdaytime（昼間）という単語を見てみましょう。実は daytime の場合、イギリス英語であってもハイフンを入れる day-time という表記は、現代ではほとんど使われません。daytime はすでに完全に一単語として定着してしまいました。nighttime は、まだイギリスにおいてハイフンが根強く残っています。このように、英語は全ての単語が一律に変化するのではなく、単語ごとに進化のスピードが異なるのです。混乱するかもしれませんが、「昼は daytime 一択、夜は地域によって nighttime か night-time」と覚えておけば完璧です。nighttime を使いましょう。現在、世界的に最も広く受け入れられている形です。IT企業のドキュメントや、アメリカのニュースサイト、SNS（InstagramやXなど）でのやり取りでは、この一単語の形が最も自然に見えます。- 例:
Check out this nighttime view from my office!
night-time を使うと「お、この人は現地のスタイルを理解しているな」と信頼感が高まります。- 例:
The study examines night-time noise pollution in London.
night time を使います。これは「夜という期間」ではなく、「夜の中の、ある特定の時間（clock time）」に焦点が当たっているからです。- 例: "Is there a specific night time you'd like to call?"
night が time を修飾する別々の単語として機能します。nighttime を使い、イギリス式なら night-time で統一してください。同じレポートの中で両方が混ざっていると、ネイティブスピーカーには「注意力が足りない」あるいは「スペルミス」のように見えてしまいます。提出前に「検索」機能を使って、表記が統一されているかチェックする癖をつけましょう。- Bad: "I'm looking for a
night timejob." - Good: "I'm looking for a nighttime job."
night と time と job をバラバラに並べたくなってしまうのです。しかし、英語のルールでは、複数の単語が合わさって一つの名詞を修飾する場合、それらを繋げて一つの形容詞ユニットにする必要があります。daytime にもハイフンを入れてしまう（過剰修正）daytime にもハイフンを入れてしまうことがあります。- Bad:
The park is crowded in the
day-time. - Good:
The park is crowded in the daytime.
night-time があるなら day-time もあるはずだ、と考えてしまう「過剰修正（Hypercorrection）」という現象です。残念ながら英語は論理的でない部分が多く、daytime はすでにハイフンが消滅した単語として定着しています。これは慣習として覚えるしかありません。nighttime を「夜中（Midnight）」の意味で使ってしまう- Confusion:
I woke up at nighttime.
at midnight や in the middle of the night を使うのが適切です。nighttime はあくまで「日没から日の出まで」という長いスパンを指す言葉です。日本語の「夜中」という言葉が持つ「遅い時間」というニュアンスをそのまま nighttime に当てはめないよう注意しましょう。nighttime のような複合語の進化プロセスを理解するために、他の似た単語と比較してみましょう。英語がいかに「バラバラの状態」から「一つの単語」へと融合していくかがわかります。night time | night-time | nighttime | 現在、イギリス式とアメリカ式が共存中。 |day time | (まれ) | daytime | ほぼ完全に daytime に統一。 |life style | (古い) | lifestyle | 現代では一単語が標準。 |web site | web-site | website | インターネット初期はバラバラだったが、今は一単語。 |ice cream | - | - | 常に二単語。繋がる気配は今のところなし。 |ice cream のようにずっと二単語のままのものもあります。nighttime はまさに、その「融合の真っ最中」にいる単語なのです。night-time に赤い波線が出ることがありますし、逆も然りです。迷ったら、より現代的でグローバルな nighttime を使うのが無難です。night と time を繋げて、一つの単語として一気に発音します。最初の night にアクセントを置くのがコツです。at night と during nighttime はどう使い分けますか？at night は「夜に」という非常に一般的な表現で、日常会話で最もよく使われます。一方、during nighttime や in the nighttime は少しフォーマル、あるいは記述的な響きがあり、「夜間という時間帯において」というニュアンスが強まります。普段の会話なら at night で十分です。nighttime、イギリス系や伝統的な欧州企業なら night-time が好まれる可能性があります。しかし、何よりも大切なのは、履歴書全体でどちらかに統一することです。一箇所でもズレがあると、細部への注意力が疑われてしまうので気をつけましょう。nighttime もそれと同じような「スタイルの選択」の問題です。この記事を参考に、自分のターゲットとする相手に合わせて、自信を持って使い分けてみてくださいね。頑張る皆さんの英語学習を、いつも応援しています！Spelling Variations by Region
| Region | Spelling | Type | Example |
|---|---|---|---|
|
United States
|
nighttime
|
Closed Compound
|
A nighttime walk.
|
|
United Kingdom
|
night-time
|
Hyphenated Compound
|
A night-time walk.
|
|
Canada
|
nighttime
|
Closed Compound
|
The nighttime sky.
|
|
Australia
|
night-time
|
Hyphenated Compound
|
Night-time safety.
|
|
Informal/Old
|
night time
|
Open Compound
|
In the night time.
|
Meanings
The period of time between sunset and sunrise when it is dark outside.
Noun Usage
The actual duration or period of the night.
“I prefer the quiet of the nighttime.”
“Animals that hunt during the night-time are called nocturnal.”
Adjectival Usage
Describing something that happens or exists during the night.
“She has a nighttime routine that helps her sleep.”
“The city offers many night-time activities for tourists.”
Reference Table
| 形式 | タイプ | 主な地域 | 使い方の例 |
|---|---|---|---|
|
`nighttime`
|
連結語（一単語）
|
アメリカ英語
|
The `nighttime` sky was full of stars.
|
|
`night-time`
|
ハイフン連結語
|
イギリス英語
|
He works a `night-time` shift at the factory.
|
|
`night time`
|
名詞句（2単語）
|
共通（やや珍しい）
|
What `night time` should we meet?
|
フォーマル度スペクトル
The candidate is required to fulfill nighttime responsibilities. (Employment)
He has a nighttime job at the hospital. (Employment)
He's on the nighttime shift. (Employment)
He's working the graveyard shift. (Employment)
Nighttime vs. Night-time の比較
どの 'Night Time' を使うべき？
形容詞として使っていますか？ (例: 'a ___ walk')
特定の時刻（時計の時間）について聞いていますか？ (例: 'What ___?')
Nighttime/Night-time の使い道
名詞として
- • The quiet of `nighttime`
- • Activities after `nighttime`
- • Waking in the `night-time`
形容詞として
- • A `nighttime` snack
- • My `night-time` routine
- • The `nighttime` sky
「夜の時間」を表す単語
アメリカ英語
- nighttime 最も一般的
イギリス英語
- night-time こちらもよく使われる
特定の時間
- night time 使用頻度は低め
レベル別の例文
I like the nighttime.
I like the nighttime.
It is cold in the nighttime.
It is cold in the nighttime.
The nighttime is for sleeping.
The nighttime is for sleeping.
Do you like the nighttime?
Do you like the nighttime?
She has a nighttime routine.
She has a nighttime routine.
The city is beautiful in the nighttime.
The city is beautiful in the nighttime.
He works a nighttime shift.
He works a nighttime shift.
I don't like driving in the nighttime.
I don't like driving in the nighttime.
Many animals are active during the nighttime.
Many animals are active during the nighttime.
The nighttime economy is important for London.
The nighttime economy is important for London.
You should wear reflective gear for nighttime running.
You should wear reflective gear for nighttime running.
The nighttime sky was full of stars.
The nighttime sky was full of stars.
The study examined nighttime sleep patterns in teenagers.
The study examined nighttime sleep patterns in teenagers.
Night-time noise levels must be kept to a minimum.
Night-time noise levels must be kept to a minimum.
The photographer captured the essence of nighttime Paris.
The photographer captured the essence of nighttime Paris.
Her nighttime anxiety made it difficult to rest.
Her nighttime anxiety made it difficult to rest.
The city's nighttime infrastructure is undergoing a major overhaul.
The city's nighttime infrastructure is undergoing a major overhaul.
Linguistic shifts often turn open compounds into closed ones, as seen with 'nighttime'.
Linguistic shifts often turn open compounds into closed ones, as seen with 'nighttime'.
The nocturnal habits of the species are strictly confined to the nighttime hours.
The nocturnal habits of the species are strictly confined to the nighttime hours.
The film's nighttime cinematography was praised by critics.
The film's nighttime cinematography was praised by critics.
The transition from 'night time' to 'nighttime' reflects the increasing pace of lexical synthesis in English.
The transition from 'night time' to 'nighttime' reflects the increasing pace of lexical synthesis in English.
The poet utilized the nighttime as a metaphor for the subconscious mind.
The poet utilized the nighttime as a metaphor for the subconscious mind.
Despite the prevalence of 'nighttime' in digital corpora, 'night-time' remains the preferred choice for British lexicographers.
Despite the prevalence of 'nighttime' in digital corpora, 'night-time' remains the preferred choice for British lexicographers.
The inherent ambiguity of nighttime visibility poses a challenge for autonomous vehicle sensors.
The inherent ambiguity of nighttime visibility poses a challenge for autonomous vehicle sensors.
間違えやすい
Learners use 'nighttime' to describe when an action happens.
Learners use 'nighttime' when they mean 'this specific night'.
Learners think 'bedtime' also needs a hyphen in the UK.
よくある間違い
I sleep in the night time.
I sleep in the nighttime.
Good night-time!
Good night!
The night time is dark.
The nighttime is dark.
I like night-time.
I like nighttime.
My night time routine.
My nighttime routine.
I work nighttime.
I work at night.
The nighttime are long.
The nighttime is long.
In the US, they use night-time.
In the US, they use nighttime.
The night-time sky (in a US publication).
The nighttime sky.
He prefers the night time's quiet.
He prefers the nighttime's quiet.
The night time evolution of the city.
The nighttime evolution of the city.
文型パターン
I love the ___ of the nighttime.
My ___ nighttime routine includes ___.
The ___ is often associated with ___.
Despite the challenges of ___ visibility, the driver ___.
Real World Usage
Enable nighttime mode to reduce blue light.
We are looking for a nighttime security guard.
Apply our nighttime cream before bed for best results.
The accident occurred during the nighttime hours.
Nighttime vibes in the city.
Experience the magic of a nighttime safari.
Use the nighttime filter for better contrast.
No nighttime parking allowed.
迷ったら一単語で書こう
形容詞のときは2単語に分けない
night time を形容詞として使ってしまうこと。「夜の散歩」と言うなら、1単語にするかハイフンを入れよう。 "Avoid saying 'a night time walk'; it should always be 'a nighttime walk'."現地のスタイルに合わせる
Using night-time shows you have a good command of regional English nuances.
アメリカ vs イギリスの違い
This is a classic American English vs. British English difference.
Smart Tips
Use 'nighttime' (one word). It is the most widely recognized and used form in digital media.
Don't worry! The spelling 'nighttime' stays the same for both in American English.
If your spellchecker flags 'night-time', check if your language setting is set to 'English (US)'.
Switch to 'at night' if you are describing when someone does something.
発音
Stress Pattern
In compound nouns like nighttime, the stress is almost always on the first syllable.
The Double 'T'
Even though there are two 't's, they are pronounced as one slightly elongated 't' sound.
Falling intonation
I love the nighttime. ↘
A definitive statement of fact or preference.
暗記しよう
記憶術
In the USA, we 'close' the door at night (nighttime). In the UK, we use a 'bridge' (night-time).
視覚的連想
Imagine the word 'night' and 'time' holding hands in America (nighttime), but standing on two sides of a small bridge in London (night-time).
Rhyme
One word for the States, a hyphen for UK mates.
Story
An American traveler and a British traveler met at dusk. The American said, 'I love the nighttime!' (one word). The Brit replied, 'Yes, the night-time is lovely' (with a hyphen). They both agreed that 'night time' with a space was just wrong.
Word Web
チャレンジ
Write three sentences about your evening routine. If you live in the US, use 'nighttime'. If you live elsewhere, use 'night-time'. Check if you accidentally added a space!
文化メモ
Americans value efficiency in spelling, which is why most compounds like 'nighttime' and 'daytime' have lost their hyphens entirely.
British English tends to be more conservative with spelling, retaining hyphens to show the history of the word's formation.
On the internet, 'nighttime' is the dominant form regardless of the user's country, likely due to the influence of US-based tech companies and autocorrect features.
Derived from Old English 'niht' (night) and 'tīma' (time).
会話のきっかけ
What is your favorite thing about the nighttime?
Describe your nighttime routine in detail.
Do you think the nighttime economy is important for your city?
How does nighttime photography differ from daytime photography?
日記のテーマ
よくある間違い
Test Yourself
nighttime はここでは「生き物（creature）」を説明する形容詞として正しく使われています。2単語の night time は形容詞としては使えません。nighttime か night-time を使います。ここでの2単語バージョンは不自然です。nighttime （またはハイフンあり）です。2単語の night time は形容詞になれません。Score: /3
練習問題
8 exercisesI enjoy the ___ air.
The ___ economy is growing in London.
Find and fix the mistake:
She has a very busy night time schedule.
The routine she does at night is long.
'Nighttime' is always used as a verb.
Pick the correct form.
A: Do you work during the day? B: No, I have a ___ job.
US vs UK
Score: /8
Practice Bank
13 exercisesIn London, the ___ economy is a major focus for the city council.
Select the most natural-sounding sentence for a casual, modern context.
The photos from our night time hike didn't turn out very well.
Translate into English: 'El turno de noche es agotador.'
Put these words in the correct order:
Match the form to the region:
What ___ do you want to leave for the airport? It should be dark by then.
Choose the sentence that fits a formal UK report:
Her favorite part of camping is the quiet of the night-time.
Arrange these words to ask a question:
Translate to English: 'Prefiero conducir de noche.'
The festival offers both daytime and ___ events.
Match the bolded word to its role:
Score: /13
よくある質問 (8)
It is rarely considered correct in modern formal writing. Most style guides insist on either `nighttime` or `night-time`.
Since IELTS accepts both British and American English, both `nighttime` and `night-time` are correct, as long as you are consistent throughout the test.
No, `nighttime` is only a noun or an adjective. You cannot 'nighttime' something.
Interestingly, `daytime` is almost always written as one word in both US and UK English. `Night-time` is more likely to keep its hyphen in the UK than `daytime` is.
No, the meaning remains exactly the same. It is purely a matter of spelling style and regional preference.
Older books or informal literature might use the two-word version, but modern standards have moved toward closing the compound.
Not necessarily. In the US, `nighttime` is used in the most formal academic and legal documents.
Think of the US as 'closing' the gap between the words to save space: `nighttime`.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
la noche / horario nocturno
Spanish uses two or more words where English uses one.
la nuit / nocturne
French relies on adjectives rather than compound nouns.
Nachtzeit
German always closes the compound, similar to the US style.
夜間 (Yakan)
Japanese uses characters to form the compound, which is conceptually similar to English.
وقت الليل (Waqt al-layl)
Arabic requires two separate words with a grammatical link.
夜间 (Yèjiān)
The logic of combining the two concepts is identical to English.
Learning Path
Prerequisites
関連動画
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