一いっ瞬しゅん間かんいっしゅんかんMeanings1nounmoment; instantRefers to a very short period of time, often used in expressions like 一瞬間に (in an instant) or 一瞬間の (momentary).彼かれは一いっ瞬しゅん間かんで姿すがたを消けした