The word 「うち」 has three faces:
| Meaning | Usage | Example |
|---|---|---|
| Home | House, home | うちに帰る (go home) |
| Inside | Within a scope | 会社のうち (within the company) |
| うちに | While (a state lasts) | 若いうちに (while still young) |
The third meaning is the N3 focus — it means "within the time window where a certain condition still holds, hurry up and do something."
Core Nuance: The Window Will Close
うちに implies "this favorable condition won't last forever" — if you don't act now, the chance is gone:
| Example | Meaning |
|---|---|
| 若いうちに、いろいろ体験します。 | While you're young, experience lots of things. |
| 忘れないうちに、メモしておこう。 | Before I forget, let me jot it down. |
| 明るいうちに、帰りましょう。 | Let's head home while it's still light out. |
Common thread: Youth fades, memories disappear, daylight ends — the window will close.
How to Connect
うちに can follow various word types, since うち is essentially a noun:
| Connection | Example |
|---|---|
| い-adjective + うちに | 若いうちに (while young) |
| な-adjective + な + うちに | 元気なうちに (while still healthy) |
| Verb ない form + うちに | 忘れないうちに (before forgetting) |
| Verb ている + うちに | 待っているうちに (while waiting) |
| Noun + の + うちに | 休みのうちに (during the break) |
うちに vs あいだに
Both can be translated as "during," but the feeling is different:
| うちに | あいだに | |
|---|---|---|
| Nuance | While this condition still holds | At some point within this period |
| Implication | Window will close | Objective time span |
| Example | 若いうちに旅行する | 夏休みのあいだに旅行する |
| Translation | Travel while still young | Travel during summer break |
Quick rule: If emphasizing "hurry before it's too late" → うちに. If simply stating "within a time period" → あいだに.
ているうちに: Gradually, Without Noticing
ているうちに means "while doing something, another thing happened without you realizing":
| Example | Meaning |
|---|---|
| テレビを見ているうちに、寝てしまった。 | I fell asleep while watching TV (without noticing). |
| 走っているうちに、雨がやんだ。 | While I was running, the rain stopped. |
Here the nuance isn't "hurry up" but rather "in the course of doing X, Y naturally happened" — a gradual, unplanned change.
Summary
- うちに = "while this condition still holds, act now"
- Implies the window will close — youth, memory, daylight are all limited
- Connects to adjectives, verb ない form, ている form, nouns
- Difference from あいだに: うちに carries urgency, あいだに is objective
Self-Check Exercises
Q1. Why does 「忘れないうちにメモしよう」 use うちに instead of あいだに?
Show Answer
Because "not yet forgotten" is a state that will disappear — if you don't write it down now, you'll forget. うちに implies "while this favorable condition still holds." あいだに simply describes an objective time span and lacks this urgency.
Q2. What does 「テレビを見ているうちに寝てしまった」 mean?
Show Answer
"I fell asleep while watching TV (without realizing it)." ているうちに here means "while doing something, another thing happened naturally." It doesn't mean "hurry and sleep while watching TV" — it describes an unplanned, gradual change.
Q3. Use うちに to say: Finish this book during the break.
Show Answer
休みのうちに、この本を読んでしまおう。 While the break (this window) is still here, finish reading the book.