偶然|ぐうぜんguuzen[0]heiban (flat)

1. na-adjective, no-adjectivecoincidence; chance; accident; fortuity
2. adverbby chance; unexpectedly; accidentally
   私は、偶然ぐうぜん旧友きゅうゆうに会あった。↗

   I met an old friend by chance.
3. noun, philosophycontingency

• SynonymたまたまNeutralAdverb, very common in speech: 'by chance, coincidentally', also 'occasionally'. 「偶然」 can serve as a noun or na-adjective as well as an adverb.
• SynonymふとNeutralCovers fleeting, unintentional thoughts or actions; 「偶然」 is about coincidence.
• SynonymたまさかWrittenWritten, with an archaic literary flavour: 'by chance, rarely'. In everyday speech 「たまたま」 is the natural choice.
• Synonym思いがけずおもいがけずNeutralStresses that the outcome is unexpected; 「偶然」 focuses on things happening to coincide.
• Synonym図らずもはからずもWrittenWritten style: 'unexpectedly, without planning', as in 「図らずも受賞した」. 「偶然」 is neutral.
• SynonymゆくりなくWrittenWritten and archaic: 'unexpectedly'. In everyday language 「思いがけず」 is used instead.
• Synonym期せずしてきせずしてWrittenWritten: 'without expecting it', often seen in 「期せずして一致」. 「偶然」 is more general-purpose.
• SynonymふいとCasualColloquial: someone suddenly or casually does something; 「偶然」 is about coincidence.
• SynonymひょいとCasualColloquial: a light, quick movement, or something happening by chance; 「偶然」 is more objective.
• SynonymはしなくもWrittenWritten: 'unexpectedly, as it happens'. In everyday speech 「偶然」 is used.
• RelatedなんとなくNeutral'For no reason one can put a finger on'; 「偶然」 is about coincidence.
• Related思わずおもわずNeutral'Involuntarily, without meaning to'; 「偶然」 describes objective coincidence.
• RelatedついNeutral'Unintentionally, despite oneself'; 「偶然」 describes objective coincidence.
• Related何気なくなにげなくNeutral'Casually, without thinking much of it'; 「偶然」 is about coincidence.
• Related巧まずしてたくまずしてWrittenWritten: 'without deliberate effort, naturally'; 「偶然」 is about coincidence.
• Related偶発的ぐうはつてきWrittenNa-adjective meaning 'accidental, sporadic', typical of accidents and incidents; 「偶然」 is more general.
• Related暗合あんごうWrittenWritten: things coinciding without either side intending it, as in 「意見が暗合する」. Everyday speech says 「偶然一致」.
• Related奇遇きぐうNeutralAn unexpected encounter, as in 「これは奇遇ですね」; 「偶然」 covers coincidence in general.
• Antonym必然ひつぜんNeutralAntonym on the axis of causality: something happens of necessity, not by chance.
• Antonym当然とうぜんNeutralAntonym on the axis of expectedness: 'naturally, as a matter of course' rather than something unexpected.
• Antonym故意こいNeutralAntonym on the axis of intent: done deliberately; common in legal contexts.

For coincidence or things happening by chance, use 「偶然」; as an adverb in speech, 「たまたま」 is the everyday choice. For an unintentional thought or action, use 「ふと」; for an unexpected encounter, 「奇遇」; for something quite unforeseen, 「図らずも」. The antonyms are 「必然」 (necessity) and 「故意」 (intent).

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

1. 思おもいがけないことが起おこること。
2. 思おもいがけないことが起おこるさま。