1.
in an instant; in a flash; instantly
Describes something happening in an extremely short moment. Formed from 一瞬 (a moment) plus the particle で marking the span of time over which something occurs.
一瞬で消えた。
It vanished in an instant.
Related Words
Compare:
あっという間に (in the blink of an eye)
Compare:
瞬時に (instantaneously)
Compare:
瞬く間に (in the blink of an eye)