How to say "instantly" in Japanese

• 一躍いちやくCommon
  adverb, noun, suru verbCovers 'instantly' only in the sense of an overnight leap to fame or success, as when someone suddenly becomes famous; it is not a general word for doing anything instantly.
  彼女かのじょは一躍いちやく有名ゆうめいになった。↗

  She suddenly became famous.
• 即刻そっこくCommon
  noun, adverbCovers 'instantly' as 'at once, without delay', with a decisive tone; typical contexts are orders, official announcements, and news reports.
  かんかんに怒おこった社員しゃいんは、即刻そっこく会社かいしゃを辞やめた。↗

  The outraged employee resigned at once.
• とっさにCommon
  adverbDescribes acting in an instant, a split-second reaction in a sudden or urgent moment, such as dodging or answering before thinking; it is about reflexive responses, not general promptness.
• すかさずCommon
  adverbEmphasizes acting without a moment's delay, right on the heels of something that has just happened — snapping a photo the instant the scene changes, or firing back a reply.
  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.
• すぐにJLPT N5approx.Common
  adverbThe all-purpose word for 'right away': use it whenever something happens or is done immediately, with no special nuance of reflex, seizing a chance, or rising to fame.
  あなたはすぐに良よくなるだろうと思おもいます。↗

  I hope you'll soon get well.

Choose 「すぐに」 for plain 'right away'; 「とっさに」 for split-second reactions, 「すかさず」 for seizing the moment right after something happens; 即刻 suits orders and announcements, and 一躍 is only for an overnight rise to fame.

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

• 一躍いちやくsuddenly (rising to fame, etc.)
• 即刻そっこくimmediately
• とっさにat once
• すかさずwithout a moment's delay
• すぐにimmediately
• 即そくinstantly
• 一思いにひとおもいにinstantly
• 間髪かんぱつimmediately
• やにわにimmediately
• 間髪を入れずかんぱつをいれずimmediately
• 一瞬にしていっしゅんにしてin an instant
• 間髪入れずかんはついれずimmediately
• 間髪おかずかんはつおかずimmediately
• 一足飛びにいっそくとびにin one go (i.e. skipping intermediate stages)