愚|ぐgu[1]atamadaka (head-high)

1. noun, na-adjectivefoolishness; silliness; stupidity; folly
   知しらないほうが幸しあわせな場合ばあいには、知しることは愚ぐである。↗

   Where ignorance is bliss, 'tis folly to be wise.
2. pronounI; me

• Synonym愚かおろかWrittenNative-Japanese word for foolish, with a literary flavor, as in 「愚かな行為」. 「愚」 itself mostly forms compounds or humble prefixes like 「愚問」「愚妻」.
• Synonym間抜けまぬけCasualCommon colloquial word for a muddled fool, with a comical tinge.
• SynonymアホCasualColloquial word for a fool, especially common in Kansai; how harsh it sounds depends on region and context.
• SynonymばかCasualThe everyday insult of choice — the commonest colloquial way to call someone an idiot.
• Synonym愚鈍ぐどんWrittenWritten word for a dull mind and slow reactions, stressing weak natural endowment.
• Synonym愚昧ぐまいWrittenWritten term for ignorance joined with foolishness, carrying contempt, as in 「愚昧な大衆」.
• Synonym愚蒙ぐもうWrittenWritten word for foolish ignorance, now rarely used.
• Synonym愚劣ぐれつWrittenWritten word for foolishness plus inferiority, a strong critical judgement, as in 「愚劣な政策」.
• Synonym愚かしいおろかしいWrittenWritten adjective for what looks foolish; close in sense to 「愚か」.
• RelatedのろまCasualColloquial insult for a slow-moving dimwit, stressing sluggishness as much as stupidity.
• Related馬鹿らしいばからしいNeutralNeutral adjective for what is absurd because it is not worth the trouble; the emphasis falls on pointlessness.
• Related浅はかあさはかNeutralNeutral word for shallow, short-sighted thinking; the stress is on insufficient thought.
• Related軽率けいそつNeutralNeutral word for rash, hasty action; it judges conduct, not natural ability.
• Related鈍いにぶいNeutralNeutral adjective for dullness of any kind — a blunt blade or a slow mind, as in 「勘が鈍い」.
• RelatedとんまCasualColloquial insult for a blockhead, with a comical tinge.
• RelatedばかばかしいCasualColloquial adjective for the absurd or ridiculous; covers both things and people's words and deeds.
• Related阿呆らしいあほらしいCasualColloquial, Kansai-flavored adjective for something laughably pointless.
• RelatedアホくさいCasualKansai colloquial adjective for something so silly it puts you off, tinged with disdain.
• Related遅鈍ちどんWrittenWritten word for sluggish, dull movement or mind, now little used.
• RelatedうすのろCasualColloquial, contemptuous word for a half-wit who is slow to understand.
• Related痴鈍ちどんWrittenWritten word for dull-witted slowness, now little used.
• RelatedとろいCasualCommon colloquial adjective for being slow or dim, with a Kansai flavor.
• Related魯鈍ろどんWrittenWritten word for dullness and low ability, rare in modern use.
• Antonym利口りこうNeutralNeutral word for cleverness and bright wits, as in 「利口な子」; the everyday opposite of being foolish.
• Antonym賢けんWrittenWritten word for wisdom and intelligence, the direct opposite of 「愚」, as in 「賢愚」.

Use 「愚」 in compounds and humble prefixes like 「愚問」「愚見」; for foolishness in written prose pick 「愚か」. For dullness of mind turn to 「愚鈍」 or 「鈍い」, for shallow thinking 「浅はか」, for rash conduct 「軽率」, for the absurd 「馬鹿らしい」. To insult, 「馬鹿」 is the everyday word, 「アホ」 in Kansai; the opposites are 「利口」 and, in writing, 「賢」.

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

1. （グ）おろかなこと。ばかなこと。
2. （グ）自分じぶんの謙称けんしょう。