1.
in the blink of an eye, in no time, before you know it
An expression describing something happening extremely quickly, so fast that one can only say "ah!" Literally: the interval of saying "ah."
あっという間に終わった。
It was over in the blink of an eye.
休みはあっという間に過ぎた。
The vacation was over before I knew it.
久しぶりに友達と話していたら、時間があっという間に過ぎた。
I was chatting with a friend I hadn't seen in a while, and time flew by in no time.
あっという間 literally means "the space of saying 'ah!'" — so brief that all you can say is "ah!"
COMMON PATTERNS:
- あっという間に: in no time (followed by a verb)
- あっという間だった: it was over in a flash
- あっという間の〜: fleeting ~ (modifying a noun)
USAGE:
Nearly always used with the particle に as あっという間に. This expression is common in both spoken and written Japanese.