疑わしい|うたがわしいutagawashii[5]nakadaka (mid-high)

1. i-adjectivedoubtful; questionable; uncertain; disputable; suspicious
   彼かれが時間じかんどおり来くるかどうかは疑うたがわしいと思おもう。↗

   I doubt if he will come on time.

• Synonym怪しいあやしいNeutralThe most common word in speech for something suspicious or off; also covers unreliable people and changing weather. Broader in use than 「疑わしい」.
• Synonym不審ふしんNeutralUsed for feeling someone is suspicious or puzzling, mostly about people's behavior, as in 「不審者」 and 「挙動不審」; 「疑わしい」 is mostly about statements and their truth.
• Synonym怪しげあやしげNeutralDescribes something that looks suspicious or of dubious origin, as in 「怪しげな薬」; stresses the impression given by appearance.
• Synonym不確実ふかくじつWrittenWritten/formal prose. Means uncertain or unreliable, mostly for predictions and information; 「疑わしい」 carries the nuance of doubting the truth.
• Synonym不確かふたしかNeutralMeans not certain or not remembered accurately, as in 「不確かな情報」; stresses lack of firm proof, not necessarily suspicion of fraud.
• SynonymあやふやCasualColloquial. Covers vague, unreliable memories and answers; stresses that something cannot be stated clearly, while 「疑わしい」 stresses it is open to doubt.
• SynonymおぼつかないNeutralSuggests prospects or ability are unreliable, as in 「成功は覚束ない」; 「疑わしい」 questions whether something is actually true.
• Synonym胡散臭いうさんくさいCasualColloquial. Describes people or talk that seem shady and untrustworthy, carrying a feeling of dislike and distrust.
• Synonym不明朗ふめいろうWrittenWritten/formal prose. Describes opaque, shady dealings such as transactions or accounting, as in 「不明朗な会計」; 「疑わしい」 has wider uses.
• Synonymきな臭いきなくさいNeutralLiterally a burnt smell; figuratively suggests war is brewing or something fishy is going on, with an ominous feel.
• Synonym心もとないこころもとないNeutralDescribes someone or something you cannot rely on, stressing subjective unease; 「疑わしい」 questions the truth objectively.
• Related曖昧あいまいNeutralMeans vague or unclear in attitude or statement, and can also suggest something improper; stresses lack of clarity, not necessarily suspicion.
• Related妙みょうNeutralMeans strange or unusual, as in 「妙な話」; stresses oddness, while 「疑わしい」 stresses that something is open to doubt.
• Related変へんNeutralCommon in speech for something strange or off; more casual than 「疑わしい」 and not specifically about truth being in doubt.
• Related不確定ふかくていWrittenWritten/formal prose. Means not yet settled, as in 「不確定要素」; an objective state of being undetermined, with no implication of doubt.
• RelatedいかがわしいNeutralSuggests shady origins or dubious character, and also indecency, as in 「いかがわしい店」; more strongly derogatory.
• Related訝しいいぶかしいWrittenWritten/formal prose. Doubt arising from finding something strange or hard to understand; stresses puzzlement, while 「疑わしい」 questions the truth.
• RelatedうろんWrittenWritten/formal prose. Describes someone who looks suspicious or of unknown background, as in 「胡乱な人物」; rare in modern usage.
• Antonym確かたしかNeutralAntonym. Means certain and reliable, and as an adverb means 'if I remember rightly'; the direct opposite of 「疑わしい」.
• Antonym明らかあきらかNeutralAntonym. Means clear, obvious and beyond doubt; the opposite of 「疑わしい」, which questions the truth.
• Antonym疑いないNeutralAntonym. Means beyond any doubt, absolutely certain; directly opposed to 「疑わしい」.

Use 「疑わしい」 when the truth or likelihood of something is in doubt. In everyday speech 「怪しい」 is the usual word for anything suspicious, 「不審」 for suspicious behavior, and 「不確か」 for being unsure. 「怪しげ」 stresses a suspicious look; 「胡散臭い」 is colloquial for shady people or talk; 「如何わしい」 adds indecency. For vagueness rather than doubt use 「あやふや」 or 「曖昧」; for unsettled matters 「不確実」 or 「不確定」. The antonyms are 「確か」, 「明らか」 and 「疑いない」.

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

1. 本当ほんとうだと思おもえない。確たしかかどうか信しんじられない。
2. 起おこりそうにない。確率かくりつが低ひくい。
3. 怪あやしい。