Translation guide
The quality of being stupid, foolish, or lacking intelligence. In Japanese, this is expressed through nouns describing the trait, adjectives for describing people/actions, and verbs for acting stupidly. The most common and versatile word is 馬鹿 (baka), but many nuanced terms exist for different contexts.
To refer to the abstract quality of being stupid, foolish, or unintelligent.
The most direct and neutral noun for 'stupidity' or 'foolishness'. Derived from the adjective 愚か (oroka). Suitable for both spoken and written contexts.
彼の愚かさには呆れる。
I'm amazed at his stupidity.
自分の愚かさを認めるのは難しい。
It's hard to admit one's own foolishness.
Noun form of 馬鹿 (baka), meaning 'stupidity' or 'idiocy'. More colloquial and emotionally charged than 愚かさ. Often used in casual speech.
そんな馬鹿さ加減には付き合えない。
I can't deal with that level of stupidity.
A formal or literary term for 'stupidity' or 'dullness'. Implies a slow-witted, obtuse nature. Rare in everyday conversation.
To call someone stupid or refer to a stupid person. Note: Japanese often uses the same word for the trait and the person.
The most common word for 'stupid person' or 'idiot'. Can be used playfully or as a strong insult depending on tone. Also used as an adjective (馬鹿な).
あいつは本当に馬鹿だ。
That guy is really stupid.
馬鹿なことを言うな。
Don't say stupid things.
Kansai-dialect equivalent of 馬鹿, but widely understood. Often used in comedy or friendly teasing. Can be more lighthearted than 馬鹿 in some regions.
A more formal or literary term for 'fool' or 'stupid person'. Less harsh than 馬鹿, but still negative. Often used in admonishments or storytelling.
Means 'blockhead' or 'dunce', emphasizing clumsiness or lack of common sense. Often used for someone who makes silly mistakes.
To describe an action or behavior as stupid, foolish, or idiotic.
Pre-noun adjectival meaning 'absurd', 'ridiculous', or 'stupid'. Used to describe actions, ideas, or situations. Very common.
それは馬鹿げた考えだ。
That's a stupid idea.
馬鹿げた間違いを犯した。
I made a stupid mistake.
Adjectival form meaning 'foolish' or 'stupid'. More formal and less emotional than 馬鹿げた. Suitable for serious contexts.
愚かな行為だった。
It was a foolish act.
Means 'trivial', 'worthless', or 'stupid' in the sense of being pointless. Often used for silly jokes or meaningless tasks.
To describe the act of pretending to be stupid or deliberately acting foolishly.
Literally 'to feign stupidity'. Used when someone pretends not to know something or acts dumber than they are.
彼は馬鹿を装って質問に答えなかった。
He played dumb and didn't answer the question.
A verb meaning 'to play dumb', 'to feign ignorance', or 'to act innocent'. Very common in casual conversation.
とぼけないで、知ってるんでしょ。
Don't play dumb, you know it, right?
Means 'to pretend not to know' or 'to ignore'. Often used when someone deliberately avoids acknowledging something.
彼は私を見ても知らんぷりをした。
He pretended not to know me even though he saw me.
English 'stupidity' is often used as a mass noun, but Japanese prefers specific constructions. For example, 'His stupidity surprised me' is better as 彼の愚かさに驚いた rather than a direct noun translation.
馬鹿 (baka) is standard Japanese and used nationwide. 阿呆 (aho) is strongly associated with the Kansai region. In Kansai, 阿呆 can be more playful, while 馬鹿 is harsher. In Tokyo, 馬鹿 is the default, and 阿呆 may sound dialectal or comedic.
馬鹿 can attach to nouns to mean 'absurdly' or 'stupidly', e.g., 馬鹿正直 (baka-shōjiki, 'honest to a fault'), 馬鹿力 (baka-jikara, 'brute strength'). This is a productive pattern in casual speech.
彼の愚かさには信じられない。
I can't believe his stupidity.
あれは馬鹿げた間違いだった。
That was a stupid mistake.
His stupidity hindered the progress of the project.
What are you doing, you idiot!
そんなことをするとは、愚か者だ。
You're a fool to do such a thing.
He has a stupid look on his face.
そんなくだらないことで怒るな。
Don't get angry over such a stupid thing.