刹那・殺那|せつなsetsuna[1]atamadaka (head-high)

1. noun, adverbmoment; instant
2. noun, Buddhismkshana; duration of a single mental event (about 1/75 second); shortest possible interval of timeorig. meaning

• Synonym瞬間しゅんかんNeutralThe everyday, all-purpose word for an instant, as in 「その瞬間」; unlike 刹那 it carries no Buddhist or literary coloring and does not stress extreme brevity.
• Synonym一瞬いっしゅんNeutralA common word in speech for a split second, as in 「一瞬の出来事」; it has none of the Buddhist coloring of 刹那.
• Synonym瞬時しゅんじWrittenA written word with a technical lean, as in 「瞬時に判断」; unlike 刹那 it has no Buddhist or literary color.
• Synonym一瞬間いっしゅんかんNeutralSame meaning as 「一瞬」, with slightly stronger emphasis; neutral in tone, without the Buddhist coloring of 刹那.
• Synonym瞬刻しゅんこくWrittenA written, classical-sounding word for an instant; used rarely.
• Synonym一弾指いちだんしWrittenA written Buddhist expression for the instant of a snapped finger; used extremely rarely.
• Synonym瞬く間またたくまNeutralThe blink of an eye, as in 「瞬く間に広まる」; used often in both speech and writing, in a neutral register unlike the literary 刹那.
• Synonym須臾しゅゆWrittenWritten and archaic in flavor: a short while, a brief moment; also the name of a number unit (10⁻¹⁵).
• Synonym転瞬てんしゅんWrittenA written word for the blink of an eye; used rarely.
• RelatedモーメントNeutralLoanword for a moment, but it leans toward physics (torque) and timing or opportunity rather than the literary brevity of 刹那.
• RelatedとっさNeutralUsed for moments of urgency — reacting in a flash, as in 「咄嗟に避ける」; the emphasis is on the response, not the span itself.
• Antonym永遠えいえんNeutralEternity — a state continuing forever; the everyday antonym of the fleeting 「刹那」.
• Antonym永久とわWrittenWritten and literary: everlastingness; an antonym of 刹那 with a poetic ring.
• Antonym永劫えいごうWrittenA written, Buddhist-leaning antonym: eons, an immensely long stretch of time set against the instant of 刹那.

Everyday instant: 「瞬間」 or 「一瞬」; 「一瞬間」 adds mild emphasis to 「一瞬」, and 「瞬く間」 fits speech and writing. 「刹那」 carries Buddhist and literary color for an extremely brief moment, as in 「刹那的な快楽」. For split-second urgency use 「咄嗟」. Written: 「瞬時」 (technical), 「瞬刻」, 「転瞬」, 「須臾」 (archaic), 「一弾指」 (very rare); 「モーメント」 leans toward physics and timing. For eternity: 「永遠」, or written 「永久」 and 「永劫」.

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

1. 仏教ぶっきょうにおける時間じかんの最小単位さいしょうたんい。
2. 極きわめて短みじかい時間じかん。瞬間しゅんかん。
3. （非ひ標準ひょうじゅん、接続せつぞく助詞じょしのように用もちいて）直後ちょくごに。
4. （非ひ標準ひょうじゅん、接続詞せつぞくしのように用もちいて）その直後ちょくご。
5. 塵劫じんこう記きでは、弾指だんしの十じゅう分ぶんの一いち。10⁻¹⁸(100京けい分ぶんの1)。