瞬間|しゅんかんshunkan[0]heiban (flat)

1. nounmoment; instant; second
   この瞬間しゅんかんは歴史れきしに記録きろくされるだろう。↗

   This moment will be recorded in history.

• Synonym一瞬いっしゅんNeutralA blink-of-an-eye span of time, also usable adverbially (「一瞬迷った」); stresses sheer brevity. 「瞬間」 can also pinpoint the exact moment something happens (「ドアを開けた瞬間」).
• Synonym刹那せつなWrittenWritten word with Buddhist overtones for an extremely short time (「刹那に判断する」「刹那的な快楽」); 「瞬間」 is more common and neutral.
• Synonym瞬時しゅんじNeutralRefers to instantaneity, as in 「瞬時に判断する」; leans toward written and technical usage.
• Synonym一瞬間いっしゅんかんNeutralSame meaning as 「一瞬」 but with stronger emphasis; in everyday speech 「一瞬」 is the usual choice.
• Synonym瞬刻しゅんこくWrittenRare written word for an instant; in everyday speech 「瞬間」 is used instead.
• Synonym一弾指いちだんしWrittenOld Buddhist term for the time it takes to snap one's fingers; rare today, seen occasionally in Buddhist or literary contexts. Everyday speech uses 「一瞬」.
• Synonym瞬く間またたくまNeutralIdiomatic expression, usually as 「瞬く間に」, for 'in the blink of an eye' (「瞬く間に売り切れた」).
• Synonym須臾しゅゆWrittenArchaic, literary word for a brief moment; very rarely used in modern Japanese.
• Synonym転瞬てんしゅんWrittenRare written word for the blink of an eye; in everyday speech 「一瞬」 is used.
• RelatedモーメントNeutralLoanword covering a moment in time and the physics sense of moment (torque); common in physics and sports commentary. Everyday speech uses 「瞬間」.
• RelatedとっさNeutralUsually as 「とっさに」, for acting in a split second before one has time to think (「とっさに身をかわす」).
• Antonym永遠えいえんNeutralEternity; the opposite of 「瞬間」 in terms of time span.
• Antonym永久とわWrittenRead 「とわ」, a literary rendering of eternity often seen in song lyrics; the opposite of 「瞬間」.
• Antonym長期間ちょうきかんNeutralA long stretch of time; contrasts with the extreme brevity of 「瞬間」.

Use 「瞬間」 for the very moment something happens, 「一瞬」 for a blink of an eye, 「瞬く間に」 for 'in the blink of an eye', 「とっさに」 for acting in a moment of urgency, and 「刹那」 for written, emotive prose; 「永遠」 is the opposite.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. ごく短みじかい時間じかん。刹那せつな。
2. 複数ふくすうの事象じしょうが、まったく同時どうじにおこること、ちょうどその時とき。