遺憾|いかんikan[0]heiban (flat)

1. na-adjective, nounregrettable; unsatisfactory; deplorable; lamentable
   それは遺憾いかんながら本当ほんとうだ。↗

   That, while regrettable, is true.

• Synonym残念ざんねんNeutralThe everyday word for 'too bad', at home in speech and writing; 「遺憾」 is more formal, for official statements or solemn apologies and censure.
• Synonym無念むねんWrittenBitter, rueful regret at being denied one's wish, with a tragic tinge as in 「無念の涙」; it also means a mind free of distracting thoughts, a sense 「遺憾」 lacks.
• SynonymこころのこりNeutralLingering misgivings or unfinished feelings afterwards, mostly about one's own state of mind; 「遺憾」 is dissatisfaction with an outcome, often in formal statements.
• Related申し訳ないもうしわけないFormalApologizes for one's own fault, common in formal settings as in 「大変申し訳なく思っております」; 「遺憾」 conveys regret without necessarily admitting fault.
• RelatedあいにくNeutralSays the timing or circumstances are unlucky, mostly adverbial as in 「あいにく雨だ」; 「遺憾」 comments on an unsatisfactory, regrettable result.
• RelatedすまないCasualColloquial apology or thanks, masculine in flavor and used to close acquaintances; 「遺憾」 is a formal statement, far more solemn in tone.
• Antonym満足まんぞくNeutralThings turning out as one wished and being content, as in 「結果に満足する」; the opposite of the unfulfilled regret of 「遺憾」.
• Antonym好都合こうつごうNeutralCircumstances being convenient or favorable to one, as in 「好都合な条件」; the opposite of things turning out disappointingly.

Use 「遺憾」 for formal, official expressions of regret, as in 「遺憾の意を表する」. For everyday 'too bad' pick 「残念」; for bitter chagrin 「無念」; for unlucky timing 「生憎」; for apologizing 「申し訳ない」.

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

1. そうなる（ならない）ように努つとめたものの、期待きたいした結果けっかが得えられず悔くいを残のこすこと。思おもいどおりに事ことが運はこばず心残こころのこりなこと。残念ざんねんであること。自分じぶんの行動こうどうを釈明しゃくめいしてわびる場合ばあいにも、相手あいての行動こうどうに対たいして非難ひなんの気持きもちを表あらわす場合ばあいにも用もちいる。
2. （「遺憾いかんなく」の形かたちで副詞ふくし的てきに）心置こころおきなく、思おもう存分ぞんぶん。