How to say "unexpected" in Japanese

• 意外いがいJLPT N3approx.Common
  na-adjective, adverb (with と), nounThe word to use when 'unexpected' means 'surprising': an outcome that defies what you expected, such as an unexpected result, answer, or turn of events. It highlights the gap between expectation and reality.
  意外いがいな結果けっかが発表はっぴょうされた。↗

  Unexpected results were announced.
• 急きゅうJLPT N4approx.Common
  na-adjectiveCovers 'unexpected' only through suddenness: its core sense is 'sudden; abrupt', so it fits an unexpected change or event that occurs without warning, and is seldom the word for a merely surprising outcome.
• 突然とつぜんJLPT N3approx.Common
  no-adjective, na-adjective, adverbDescribes something that happens abruptly, with no lead-up; its 'unexpected' nuance comes from the sheer lack of warning, as with an unexpected visit or announcement, rather than from surprise at the result.
  すべて突然とつぜん起おこった。↗

  Everything happened all at once.
• とんだJLPT N1approx.Common
  pre-noun adjectivalCovers 'unexpected' in the sense of an unwelcome surprise: something that turns out to be an unexpected — and typically annoying or embarrassing — instance of its kind, a mishap or blunder you never saw coming.
• 不意ふいJLPT N1approx.Common
  na-adjective, no-adjectiveStresses that something was unforeseen — it catches you off guard because there was no chance to anticipate it. Fits an unexpected visitor, question, or move that takes a person by surprise.
  砦とりでは不意ふいに攻撃こうげきされた。↗

  The fort was attacked by surprise.

Choose 意外 when something defies expectation and surprises you; 急 and 突然 when it simply happens suddenly, without warning; 不意 when it catches someone off guard; 「とんだ」 for an unexpected but unwelcome mishap.

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

• 意外いがいunexpected
• 急きゅうsudden
• 突然とつぜんabrupt
• とんだunexpected
• 不意ふいsudden
• にわかsudden
• 望外ぼうがいunexpected (joy, success, etc.)
• 予想外よそうがいunexpected
• 思いがけないおもいがけないunexpected
• 予期せぬよきせぬunexpected
• 不慮ふりょunforeseen
• とんでもないunthinkable
• 不測ふそくunexpected
• もっけunexpected
• 意想外いそうがいunexpected
• 不期ふきunexpected
• 慮外りょがいunexpected
• 思いもよらないおもいもよらないunexpected
• 思わぬおもわぬunexpected
• 予定外よていがいunexpected
• 意表外いひょうがいunexpected
• 思っても見ないおもってもみないunexpected
• 思いもかけないおもいもかけないunexpected
• 予期しないよきしないunexpected (e.g. results)
• 念無しねんなしunexpected
• ひょんなstrange
• 忽然こつぜんsudden
• 出し抜けだしぬけall of a sudden
• 突発的とっぱつてきsudden
• 卒然そつぜんsudden
• とんでもunthinkable
• ふとしたimpulsive
• 時ならぬときならぬunthought of
• 思ってもいないおもってもいないunanticipated
• 心当たりのないこころあたりのないcompletely unknown
• 忽焉こつえんsudden
• 非日常的ひにちじょうてきextraordinary
• 変へんunexpected
• 案外あんがいunexpected
• 皮肉ひにくunexpected
• あらぬunexpected
• どうかしたslightest