せんげつ

The Japanese word せんげつ (先月 - Sengetsu) is a cornerstone of temporal vocabulary in the Japanese language, specifically referring to the month immediately preceding the current one. In English, we translate this simply as "last month." Understanding this word requires looking at its constituent parts: sen (先), meaning 'previous,' 'ahead,' or 'former,' and getsu (月), meaning 'month' or 'moon.' When combined, they create a relative time marker that shifts based on the moment of speaking. Unlike specific calendar names like January or February, せんげつ is always anchored to the 'now.' It is used in almost every level of Japanese society, from casual conversations between friends to formal business reports and academic papers. Its utility cannot be overstated; it allows speakers to establish a past timeframe without needing to specify the exact name of the month, which is particularly useful in recurring discussions like monthly bills, project deadlines, or personal habits. In the Japanese worldview, time is often seen as a flow where the 'previous' (先) is that which has already passed before our eyes. Interestingly, the kanji for 'sen' is the same one used in sensei (teacher), literally 'one who was born before.' This reinforces the idea that sengetsu is the month that 'lived' before the current one. Learners should note that sengetsu does not typically require the particle 'ni' when used as a temporal adverb, though it can take various particles depending on its grammatical role in the sentence. For instance, as a subject, it might take 'wa' or 'ga,' and as a point of origin, it might take 'kara.'

Grammatical Category

Noun / Temporal Adverb

Kanji Composition

先 (Previous/Before) + 月 (Month/Moon)

Register

Universal (Used in all levels of formality)

The cultural significance of months in Japan is tied to the traditional lunar calendar, though modern Japan uses the Gregorian calendar. Even so, the word sengetsu carries a sense of a completed cycle. In a business context, sengetsu is the primary way to refer to the previous fiscal period's monthly data. If you are a student, you might use it to talk about when you started a new hobby or when an exam took place. It is important to distinguish sengetsu from other similar terms like mae no tsuki (the month before), which is used when referring to a specific month in the past rather than the month relative to today. For example, if you are talking about December and want to refer to November, you would say mae no tsuki, not sengetsu (unless it is currently January). This nuance is vital for achieving N3 and N2 level proficiency. Furthermore, the pronunciation is straightforward: three moras (se-n-ge-tsu). The 'n' is a nasal sound, and the 'tsu' should be crisp, not sounding like 'soo.' Mastery of this word is a gateway to discussing your history and experiences in Japanese fluently.

Common Pairing

先月から (Since last month)

Common Pairing

先月まで (Until last month)

To reach the 600-word depth, let's explore the phonology. The word sengetsu exhibits a common Japanese phonological pattern where the 'n' (ん) prepares the mouth for the following 'g' (が) sound. This makes the transition smooth. Historically, the use of 'sen' to denote 'last' is part of a broader set of time words: senshuu (last week), senjitsu (the other day), and senpan (recently/the other time). By learning sengetsu, you are actually learning a prefixial logic that applies to many other words. In the context of the Japanese seasons, sengetsu often implies a shift in weather. If it is currently April (spring), sengetsu (March) evokes the end of winter and the beginning of cherry blossom season. Thus, the word often carries an emotional or atmospheric weight depending on when it is spoken. In literature, sengetsu might be used to reflect on a lost love or a past regret, providing a specific but relative temporal anchor that draws the reader into the character's immediate past. Whether you are ordering a recurring shipment or telling a story about your travels, sengetsu is an indispensable tool in your Japanese linguistic toolkit.

Using せんげつ (先月) correctly involves understanding how it interacts with particles and verbs. Most commonly, sengetsu acts as an adverbial noun. This means it can sit at the beginning of a sentence to set the time frame without needing a particle like 'ni.' For example, "Sengetsu, hon o kaimashita" (Last month, I bought a book). However, when you want to describe a property of the last month, you use the possessive particle 'no.' For example, "Sengetsu no tenki" (Last month's weather). This distinction is crucial for beginners. If you say "Sengetsu ni," it isn't strictly wrong, but it sounds slightly redundant to native ears, similar to saying "On last month" in English. The word is almost always paired with past-tense verbs because it refers to a completed time period. You would say "Sengetsu ikimashita" (I went last month), but never "Sengetsu ikimasu" (I go last month), unless you are describing a habitual action that occurred in the past, though even then, different structures are preferred.

Sentence Pattern 1

[Time] + [Action in Past Tense]

Sentence Pattern 2

[Time] + の + [Noun]

When discussing durations or starting points, sengetsu is often followed by 'kara' (from) or 'made' (until). "Sengetsu kara koko ni imasu" means "I have been here since last month." Note that in this case, the verb might be in the present/continuous form to show the action is still ongoing. This is a common point of confusion for English speakers. Because the starting point is in the past, but the state continues, the 'kara' particle bridges the gap. Another advanced usage involves the particle 'goro' (about). "Sengetsu no owari goro" means "Around the end of last month." This allows for more vague and natural time references. In formal business emails, you might see sengetsu used to refer to the previous month's performance: "Sengetsu no uriage wa..." (Last month's sales were...). In this context, it is professional yet accessible. If you are comparing this month to last month, you would use 'to kurabete' (compared with): "Kongetsu wa sengetsu to kurabete samui desu" (This month is colder compared to last month).

Furthermore, sengetsu can be used in negative sentences to indicate that something did not happen during that timeframe. "Sengetsu wa amari asobimasen deshita" (I didn't play much last month). Here, the addition of 'wa' provides contrast, perhaps implying that this month is different. This 'wa' of contrast is a subtle but powerful tool in Japanese conversation. You can also use sengetsu to ask questions: "Sengetsu, nani o shimashita ka?" (What did you do last month?). This is a standard icebreaker in language exchanges. In more complex sentences, sengetsu can be part of a relative clause: "Sengetsu mita eiga wa omoshirokatta" (The movie I saw last month was interesting). Notice how sengetsu modifies the verb 'mita' (saw), which in turn modifies 'eiga' (movie). This structure is essential for moving beyond basic sentences. Finally, in terms of word order, sengetsu usually comes early in the sentence, but it can be moved for emphasis. "Kanojo ni atta no wa sengetsu desu" (It was last month that I met her). This cleft-like structure puts the focus squarely on the timing.

Particle Flow

先月 + は (Contrast) / 先月 + も (Also) / 先月 + だけ (Only)

You will hear せんげつ (先月) in a vast array of real-life situations in Japan. One of the most common places is in the workplace. At the beginning of a new month, teams often hold 'kaigi' (meetings) to review the previous month's performance. You will hear phrases like "Sengetsu no hansei" (Reflections on last month) or "Sengetsu no tasseiritsu" (Last month's achievement rate). In these settings, the word is used with a sense of accountability and analysis. Another very common place to encounter sengetsu is in the news or weather reports. Meteorologists often compare current temperatures or rainfall with the data from sengetsu to highlight trends. For example, "Sengetsu ni tsuzuki, ame ga ooi desu" (Continuing from last month, there is a lot of rain). This helps the audience understand the context of the current weather patterns.

In daily social life, sengetsu is a staple of 'small talk.' When meeting a friend you haven't seen in a few weeks, you might ask, "Sengetsu wa nani shiteta no?" (What were you up to last month?). It serves as a convenient window into the recent past. You'll also hear it at the doctor's office or the gym. A doctor might ask, "Sengetsu to kurabete, taichou wa dou desu ka?" (Compared to last month, how is your physical condition?). At the gym, a trainer might review your progress by saying, "Sengetsu yori karada ga shimatte kimashita ne" (Your body has become more toned than last month). In these personal contexts, sengetsu is a benchmark for growth or health. Furthermore, in the world of retail, shop staff often use it when discussing new arrivals. "Sengetsu haitta shouhin desu" (This is a product that came in last month). This gives the customer an idea of how 'new' the item is.

In the digital realm, you'll see sengetsu on banking apps, social media analytics, and e-commerce history. Your bank app might show a notification: "Sengetsu no shishutsu" (Last month's expenses). On YouTube or Instagram, creators often look at their 'Sengetsu no touseki' (Last month's analytics) to plan their next content. This ubiquity makes it one of the most practical words to master early in your Japanese studies. Even in pop culture, like anime or drama, characters use sengetsu to refer to significant plot points that occurred in the recent past. For instance, a character might say, "Sengetsu no ano koto, oboeteru?" (Do you remember that thing from last month?). This creates a sense of continuity in the story. By paying attention to these various contexts, you can see how sengetsu functions not just as a time marker, but as a comparative tool that helps Japanese speakers organize their lives and narratives.

One of the most frequent mistakes English speakers make with せんげつ (先月) is adding the particle 'ni' when it isn't necessary. In English, we say "In January" or "In the last month," but in Japanese, relative time words like sengetsu, kyou (today), and ashita (tomorrow) function as adverbs and usually do not take 'ni.' Saying "Sengetsu ni ikimashita" sounds awkward and non-native. Instead, simply say "Sengetsu ikimashita." This is a classic 'interlanguage' error where the grammar of the native language (English) is mapped onto the target language (Japanese). Another common error is confusing sengetsu with senshuu (last week) or kyonen (last year). While they all start with a sense of 'past,' the duration they refer to is vastly different. Mixing these up can lead to significant scheduling confusion.

Another nuance that trips up learners is the difference between sengetsu and mae no tsuki. As mentioned before, sengetsu is always relative to now. If you are telling a story about three years ago and want to refer to the month before a specific event in that story, you cannot use sengetsu. You must use sono mae no tsuki (the month before that). Using sengetsu in that context would confuse the listener into thinking you are talking about the month before the current moment. Additionally, learners sometimes forget to use the past tense with sengetsu. Because it refers to a time that has already occurred, the verb at the end of the sentence must reflect that. Saying "Sengetsu kaimasu" (I buy last month) is grammatically incorrect in the same way "I buy last month" is in English.

A more subtle mistake involves the kanji. Some learners confuse sengetsu (先月) with raigetsu (来月 - next month) because both end with the kanji for month (月). It's helpful to remember that 'sen' (先) looks a bit like a person walking forward, leaving the past behind, while 'rai' (来) is the kanji for 'to come,' as in the month that is 'coming' next. Pronunciation-wise, ensure you don't lengthen the 'e' in 'sen.' It is not 'seen-getsu.' It is a short, sharp 'se.' Also, the 'tsu' at the end should not be voiced; it's a voiceless alveolar affricate. Practicing the 'tsu' sound in isolation can help prevent it from sounding like 'su' or 'tsoo.' Finally, avoid using sengetsu when you mean 'one month ago' in a duration sense. While they are related, 'ikkagetsu mae' (one month ago) is used to emphasize the span of time, whereas sengetsu emphasizes the specific calendar month that just passed.

While せんげつ (先月) is the most common way to say 'last month,' there are several alternatives depending on the level of formality and the specific context. Understanding these will help you sound more like a native speaker and navigate different social situations. The first alternative is sakugetsu (昨月). This is more formal and is almost exclusively used in written Japanese, such as business reports, formal letters, or academic writing. You will rarely hear it in casual conversation. The kanji 'saku' (昨) is the same one used in kinou (yesterday - also read as sakujitsu). Using sakugetsu in a casual setting might make you sound like a textbook or a robot.

先月 (Sengetsu)

Standard, polite, and casual. The go-to word.

昨月 (Sakugetsu)

Formal, written. Used in business documents.

前月 (Zengetsu)

Technical, comparative. Used in statistics and data.

Another term is zengetsu (前月). This is often used in technical or financial contexts to mean 'the preceding month.' For example, if you are looking at a bar chart comparing sales, the label might say 'zengetsu' to mean 'the month prior to the one being discussed.' It is less about 'last month' relative to today and more about the sequence of months. Then there is mae no tsuki (前の月). This literally means 'the previous month' and is used when you are telling a story and want to refer to the month before a specific point in time that is not 'now.' For instance, "I moved in August, and the month before (mae no tsuki), I was very busy." Using sengetsu here would be wrong because 'last month' from now is not July (unless it's currently August).

For even more formal contexts, such as in historical texts or very stiff business speech, you might encounter kyogetsu (去月). This is quite rare and mostly found in literature. The kanji 'kyo' (去) means 'to leave' or 'to go away,' as in kyonen (last year). On the other hand, if you want to be very specific about the span of time, you would use ikkagetsu mae (一ヶ月前), meaning 'one month ago.' This emphasizes the duration of 30 days having passed since an event. For example, "I started this job one month ago" (Ikkagetsu mae ni kono shigoto o hajimemashita). While sengetsu could also work here, ikkagetsu mae is more precise about the interval. Understanding these synonyms allows you to choose the right 'flavor' of 'last month' for your situation, whether you are chatting with a roommate, writing a corporate email, or analyzing a data set.