How to say "unlikely" in Japanese

Choosing the right word
  • とんだJLPT N1approx.Common
    pre-noun adjectivalCovers 'unlikely' only via the sense of an unexpected or strange outcome, often one that turns out badly or absurdly. It is really the word for 'an unlikely mishap', so it seldom serves for neutral improbability.
  • suffix, na-adjectiveThis is the closest match for the plain predictive sense of 'unlikely': something seems not to exist, happen, or be possible. Use it when you want to say an event, result, or opportunity appears improbable.
    「宝たからくじでも買かう?」「俺おれ、ギャンブル運うんとか無なさそうだしなぁ」↗
    "Buy a lottery ticket or something?" "Well, I don't think I've got much luck with gambling."
  • 怪しいあやしいJLPT N2approx.Common
    i-adjectiveIts core senses are doubtful, unsure, or uncertain; 'unlikely' is only a marginal extension. Reach for it when something is questionable or untrustworthy, not as your usual way to say that something is improbable.
    彼かれが時間じかんどおりに来くるかどうかは私は怪あやしいと思おもう。↗
    I question whether he'll come in time.

Use 「なさそう」 for the ordinary predictive sense of 'unlikely' (something seems improbable); 「とんだ」 for an unexpected, outlandish outcome; and 「怪しい」 mainly when something is doubtful or suspect rather than truly unlikely.

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

Japanese equivalents
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JLPT vocabulary levels are community estimates, not official (no official lists have been published since the 2010 revision).

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