Translation guide
The quality of being unwise, lacking good judgment, or acting without thinking. In Japanese, this concept is expressed through nouns describing the trait, adjectives describing the state, and verbs describing foolish actions.
Expressing the abstract quality of being foolish, unwise, or lacking intelligence.
The most direct and common noun for 'foolishness' or 'stupidity'. Neutral in formality.
彼の愚かさには呆れる。
I'm amazed at his foolishness.
Colloquial noun for foolishness, derived from 馬鹿 (idiot). Slightly more casual and direct than 愚かさ.
自分の馬鹿さに気づいた。
I realized my own foolishness.
A less common, slightly literary noun form. Can sound more abstract or poetic.
人間の愚かしさを描いた小説。
A novel depicting human foolishness.
Referring to a specific foolish action, mistake, or behavior rather than the abstract trait.
Literally 'foolish act'. Used for a specific action that is unwise or reckless. Common in news and formal contexts.
彼の愚行は会社に大きな損害を与えた。
His foolish act caused great damage to the company.
Colloquial phrase meaning 'a stupid thing' or 'foolishness'. Very common in spoken Japanese.
馬鹿なことをしてしまった。
I did something foolish.
Formal phrase meaning 'foolish act'. More explicit than 愚行, often used in writing.
それは愚かな行為だった。
That was a foolish act.
Describing someone as being in a foolish state or condition, often temporarily.
Adjectival phrase meaning 'is foolish'. Used to describe a person, action, or idea. The noun form is 愚かさ.
そんなことをするなんて愚かだ。
It's foolish to do such a thing.
Casual adjectival phrase meaning 'is stupid/foolish'. Very common in everyday speech.
あいつは本当に馬鹿だ。
That guy is really foolish.
Describing a person who is habitually foolish or lacks wisdom.
愚か (oroka) is more formal and often used in writing or serious contexts. 馬鹿 (baka) is casual, common in speech, and can be insulting. For abstract 'foolishness', 愚かさ is neutral; 馬鹿さ is colloquial.
English 'foolishness' is often best expressed with an adjective phrase like 愚かだ or a noun like 愚かさ. Direct translations like フーリッシュネス do not exist in natural Japanese.