いきなり・行き成りikinari

1. adverb, no-adjectiveabruptly; suddenly; all of a sudden; without warning
   そのタクシーはいきなり左ひだりに曲まがった。↗

   The taxi abruptly turned left.

• Synonym突然とつぜんNeutralThe most versatile of the group; works both as a na-adjective and as an adverb. 「いきなり」 is the more colloquial choice and stresses that there was no lead-up at all.
• Synonym突如とつじょWrittenWritten/formal prose, common in news reports and novels. 「いきなり」 is the more colloquial word.
• SynonymたちまちWrittenWritten/formal prose; describes turning into a state in the blink of an eye, as in 「たちまち売り切れる」. 「いきなり」 stresses the lack of any lead-up.
• SynonymにわかにWrittenWritten/formal prose; describes a situation changing all at once. 「いきなり」 is more colloquial.
• Synonym不意にふいにNeutralStresses the unexpected, catching someone off guard. 「いきなり」 focuses on skipping the usual steps and coming with no lead-up.
• Synonym急にきゅうにCasualColloquial; covers suddenness and rapidity in general. 「いきなり」 puts more weight on jumping straight to something.
• Synonym忽然こつぜんWrittenWritten/formal prose, used mostly for things appearing or vanishing. 「いきなり」 is more colloquial.
• Related急激きゅうげきNeutralA na-adjective for changes that are both fast and sharp. 「いきなり」 stresses that nothing presaged the event.
• Related急きゅうNeutralA na-adjective covering sudden and urgent things, as in 「急な話」. 「いきなり」 is an adverb.
• RelatedふとWrittenWritten/formal prose; mostly modifies thoughts or glances arising unbidden. 「いきなり」 stresses the abruptness.
• RelatedパッとCasualColloquial mimetic word; something happening in a flash, in an instant. 「いきなり」 stresses the absence of any lead-up.
• RelatedさっとCasualColloquial; brisk, nimble actions, or wind and rain springing up suddenly. 「いきなり」 stresses the abruptness.
• RelatedやにわにWrittenWritten/formal prose; acting on the spot, without warning. Close in sense to 「いきなり」 but more old-fashioned and literary.
• RelatedとみにWrittenWritten/formal prose; describes a degree or state changing at a stroke. 「いきなり」 focuses on starting right in with something.
• Related突としてとつとしてWrittenWritten/formal prose and rare; simply means 'suddenly'. In everyday speech use 「いきなり」 or 「突然」.
• RelatedふいとCasualColloquial; doing something suddenly and offhandedly. 「いきなり」 is the more common word.
• RelatedふっとCasualColloquial; something happening in an unthinking instant. 「いきなり」 puts more weight on the abruptness.
• RelatedつとWrittenWritten/formal prose, mostly in novel narration; sudden movements like rising or reaching out in one motion. Rare in everyday speech — use 「いきなり」 or 「さっと」.
• RelatedついとCasualColloquial; a quick, light movement done in one motion. Carries a literary flavor.
• RelatedひょいとCasualColloquial; a light, quick movement, or something happening by chance. 「いきなり」 stresses the abruptness.
• RelatedばっとCasualColloquial mimetic word; something bursting out or spreading in one sudden motion. 「いきなり」 stresses the lack of any lead-up.

Use 「いきなり」 for something that happens with no lead-up, abruptly — it fits both people's actions and changes like the weather, as in 「いきなり雨が降り出した」. To state suddenness objectively, use 「突然」 or 「急に」; in written or formal prose, 「突如」 or 「にわかに」. For a change that takes effect in an instant, reach for 「たちまち」.

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

1. 事ことが直前ちょくぜんの事態じたいと関係かんけいなく急きゅうに起おこる様さま。
2. （方言ほうげん、宮城みやぎ）とても。非常ひじょうに。
3. 事ことの成り行なりゆきに任まかせていること。
4. 事ことの成り行なりゆきに任まかせている様さま。