1.
once, when once
Used to indicate that once something happens, a consequence follows.
一旦決めたら最後までやる。
Once I've decided, I see it through to the end.
一旦火がつくと、なかなか消えない。
Once it catches fire, it's hard to put out.
一旦約束したことは守るべきだ。
You should keep a promise once you've made it.
2.
for the time being, temporarily
For a short period before continuing or changing.
一旦休憩しましょう。
Let's take a break for now.
一旦休憩しましょう。
Let's take a break for now.
一旦帰ってから出直します。
I'll go home first and then come back.
USAGE: 一旦 has two main uses:
1. CONDITIONAL (once...): Often followed by と or ば
- 一旦〜と/ば (once ~ happens)
- Emphasizes that something triggers an irreversible or significant change
2. TEMPORARY (for now): Indicates a pause before continuing
- 一旦止める (to stop temporarily)
- 一旦保留にする (to put on hold for now)
COMMON PATTERNS:
- 一旦〜したら (once you do ~)
- 一旦家に帰る (to go home first)
- 一旦落ち着く (to calm down for a moment)