不適当|ふてきとうfutekitou[2]nakadaka (mid-high)

1. na-adjective, nouninadequacy; inappropriateness; unfitness; impropriety
   その水みずは飲のむのに不適当ふてきとうだ。↗

   The water is not fit to drink.

• Synonym不釣合いふつりあいNeutralMeans a mismatch or disparity; focuses on things being out of proportion or poorly paired, rather than on impropriety.
• Synonym不適ふてきWrittenMeans unsuitability; a shorter, written-style equivalent of 「不適当」, found mainly in formal prose.
• Synonym場違いばちがいNeutralMeans out of place or incongruous; focuses on not suiting the occasion or setting.
• Synonym不穏当ふおんとうNeutralDescribes remarks, handling or conduct as improper or imprudent, as in 「不穏当な発言」; suggests a lack of prudence.
• Synonym不相応ふそうおうNeutralRefers to being out of keeping with one's status or ability, as in 「分不相応」; focuses on what befits one's station.
• Synonym不適切ふてきせつNeutralMeans inappropriate, as in 「不適切な発言」 or 「不適切な処理」; close to 「不適当」 and largely interchangeable with it.
• SynonymそぐわないNeutralMeans ill-suited or out of harmony; focuses on clashes with atmosphere or personality, and is typically used in the negative form.
• Synonym似気無いにげないWrittenMeans unlike someone or unbefitting them; written in style and not often used.
• Antonym適当てきとうNeutralAntonym: means suitable or appropriate, but colloquially also sloppy or half-hearted; stands opposite to 「不適当」.
• Antonym適切てきせつNeutralAntonym: means apt, fitting or appropriate; stands opposite to 「不適当」.

For 'unsuitable' or 'inappropriate', use 「不適当」, which leans toward written style. 「不適切」 is close to it and largely interchangeable. Say 「場違い」 when something doesn't fit the occasion, and 「不相応」 when it doesn't match one's status.

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

1. 適当てきとうでないこと。不適ふてき。