荒唐無稽|こうとうむけいkoutoumukei[5]nakadaka (mid-high)

1. na-adjective, nounabsurd; nonsensical; preposterous
   荒唐無稽こうとうむけいと皆みなに言いわれた彼かれのビジネスプランだけど、今いまとなっては我々われわれの不明ふめいを恥はじるしかないのかね。↗

   Every one of us who ridiculed his business plan as a bunch of hokum should be embarrassed we did.

• Synonym馬鹿らしいばからしいCasualColloquial: something seems so silly it is not worth doing, as in 「馬鹿らしくてやってられない」.
• SynonymむちゃくちゃCasualColloquial: reckless, absurd, or extreme; stresses sheer intensity.
• Synonym無茶むちゃCasualColloquial: wild, reckless behaviour; stresses rashness of actions.
• SynonymめちゃくちゃCasualColloquial: a complete shambles or utterly senseless; stresses the chaos.
• SynonymばかばかしいCasualColloquial: foolish and laughable, not worth a second thought, often tinged with irritation; 「荒唐無稽」 is written prose for baseless nonsense.
• Synonym阿呆らしいあほらしいCasualColloquial with a Kansai flavour; means the same as 「馬鹿らしい」 — absurd and laughable.
• Synonym馬鹿げたばかげたNeutralNeutral: absurd and foolish, as in 「馬鹿げた話」; tends to pass judgement on a claim or story.
• Synonym無稽むけいWrittenWritten prose: simply means unfounded; mostly seen inside 「荒唐無稽」 and seldom used on its own.
• RelatedめちゃめちゃCasualColloquial: a chaotic mess, or an intensifier; stresses disorder or degree rather than lack of basis.
• Related不合理ふごうりWrittenWritten prose: illogical or irrational, suited to cool analysis, as in 「不合理な制度」.
• Related理不尽りふじんNeutralNeutral: unreasonable and arbitrary, often about unfair treatment, as in 「理不尽な要求」.
• Related非常識ひじょうしきNeutralNeutral: lacking common sense, often about flouting social norms, as in 「非常識な人」.
• Related滑稽こっけいNeutralNeutral: comical and laughable; stresses being funny rather than having no basis.
• RelatedアホくさいCasualColloquial: so stupid it saps your will to bother, carrying a note of exasperation.
• Antonym堅実けんじつWrittenAntonym, written prose: steady and dependable, which sets it against 「荒唐無稽」 and its baseless flights of fancy.
• Antonym現実的げんじつてきNeutralAntonym: realistic and workable, standing against the headword's outrageousness.

For something silly and laughable, say 「ばかばかしい」. In written or formal prose, 「荒唐無稽」 labels baseless, wildly unrealistic nonsense, as in 「荒唐無稽な話」 or 「荒唐無稽な設定」. For outrageous unreasonableness pick 「理不尽」; for the realistic opposite, 「現実的」.

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

1. 根拠こんきょがなく、現実味げんじつみが感かんじられないこと。また、そのさま。「荒唐こうとう」も「無稽むけい」も、「根拠こんきょがないこと」の意い。