すかさず・透かさずsukasazu[0]heiban (flat)

1. adverbwithout a moment's delay; at once; immediately; instantly; promptly; without hesitation
   彼かれがうろたえてるすきにすかさず彼女かのじょは逃にげた。↗

   She took advantage of his confusion to escape.

• Synonym直ちにただちにWrittenWritten or formal: 'immediately', as in notices like 「直ちに避難」. Unlike 「すかさず」, it does not stress seizing a moment of opportunity.
• SynonymすぐにNeutralThe most colloquial way to say 'right away'. It does not stress catching a gap or seizing the moment the way 「すかさず」 does.
• SynonymすぐさまNeutral'Immediately' with a tighter, slightly more written feel than 「すぐに」. It does not stress seizing the moment the way 「すかさず」 does.
• Synonym即時そくじNeutral'Instant/real-time', common in technical and trading contexts like 「即時反映」. Functions as both a noun and an adverb, unlike the adverb 「すかさず」.
• Synonym即刻そっこくFormalFormal, often with a commanding tone as in 「即刻退去」. Harder and stiffer than 「すかさず」.
• Synonym即座にそくざにNeutral'On the spot' — fits quick answers and decisions, as in 「即座に答える」「即座に決断する」. Stresses fast reaction rather than seizing an opening.
• SynonymすぐNeutralThe most common everyday word for 'soon/right away'; it can also mean physically close. It does not stress seizing the moment.
• Synonym直にじきにNeutral'Before long' — points to something happening in the near future, not to an action following immediately on the heels of another.
• SynonymやにわにWrittenLiterary and old-fashioned, mostly in novels: suddenly, without warning, with a sense of surprise. 「すかさず」 lacks that abrupt, unexpected feel.
• Synonym時を移さずときをうつさずWrittenA written set phrase meaning 'without delay', close in sense to 「すかさず」 but without its nuance of taking advantage of the moment.
• Synonym直様じきさまNeutralAn old-fashioned colloquial 'at once', rarely heard today; in daily speech 「すぐ」 is the normal choice.
• Related早速さっそくNeutral'Right away' in the sense of getting started on something new, as in 「早速始めよう」. It has no implication of seizing a chance.
• RelatedたちまちNeutral'In an instant' — stresses how quickly something changes into a new state; the subject is usually a thing, not a person acting.
• RelatedとっさにNeutralAn instinctive, split-second reaction when there is no time to think. It is not a deliberate seizing of the moment as with 「すかさず」.
• RelatedほどなくNeutral'Before long' — a much looser time frame than 「すかさず」; the follow-up is not immediate.
• RelatedたちどころにNeutral'In no time, on the spot' — covers both effects taking hold and actions, as in 「立ちどころに治る」. No nuance of seizing an opportunity.
• Related即そくNeutralMostly a prefix or compact colloquial form in words like 「即決」「即返信」. Brief and clipped rather than a full adverb like 「すかさず」.

Use 「すかさず」 when someone seizes the moment and acts without hesitation right after something happens. For everyday 'right away', 「すぐ」 or 「すぐに」 is the default. In formal or written notices choose 「直ちに」; for a commanding tone, 「即刻」. For an on-the-spot reaction or decision, 「即座に」; for an instinctive split-second response, 「とっさに」. 「早速」 starts something new, 「たちまち」 stresses rapid change, 「ほどなく」 and 「じきに」 mean 'before long', and 「即時」 is the technical 'real-time' term.

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

1. すぐに、ためらわずに行動こうどうする様子ようす。