Translation guide
This guide covers how to describe a stupid person in Japanese, from mild and playful to harsh and insulting. It includes common words, phrases, and patterns, with notes on politeness and context.
To call someone stupid in a general sense, ranging from light teasing to strong insult.
The most common and versatile word for 'stupid' or 'idiot'. Can be used playfully among friends or as a serious insult. Often used in compounds.
彼は馬鹿だ。
He is stupid.
馬鹿なことを言うな。
Don't say stupid things.
Similar to 馬鹿 but more common in Kansai dialect. Often used jokingly. Can be written as 阿呆 or あほ.
あほやなあ。
You're such an idiot. (Kansai dialect)
Means 'fool' or 'blockhead', emphasizing clumsiness or lack of sense. Less harsh than 馬鹿 in some contexts.
間抜けな顔をしている。
He has a stupid look on his face.
A more formal or literary term for 'fool'. Often used in serious or dramatic contexts.
彼は愚か者だ。
He is a fool.
To call someone silly or dumb in a light-hearted, non-offensive way.
A softer, more affectionate version of 馬鹿, often used for someone who is endearingly silly.
うちの犬はおバカでかわいい。
Our dog is adorably dumb.
Slang for 'useless' or 'broken', often used affectionately for a clumsy or silly person. Originally means 'junk' or 'piece of crap'.
彼はぽんこつだけど憎めない。
He's a bit of a mess, but you can't hate him.
Short for 天然ボケ, meaning someone who is naturally airheaded or says funny things without meaning to. Not necessarily stupid, but often perceived as such.
To strongly insult someone's intelligence, often in anger or contempt.
Literally 'trash' or 'scum'. A very strong insult implying worthlessness. Use with extreme caution.
あんなクズは死ねばいい。
Scum like that should just die.
Similar to クズ, meaning 'dregs' or 'scum'. Very insulting.
お前はカスだ。
You're scum.
Means 'low intelligence' or 'feeble-minded'. A direct and harsh insult, often used in online arguments.
To say someone is not quick to understand, rather than outright stupid.
Means 'dull' or 'slow', often used for someone who is slow on the uptake. Can refer to physical or mental slowness.
彼は頭の回転が鈍い。
He is slow-witted.
Colloquial term for 'slow' or 'sluggish', often used for someone who is mentally or physically slow.
Means 'slowpoke' or 'dunce', implying both mental and physical slowness. Mildly insulting.
のろまな奴だな。
What a slowpoke.
To describe someone who is stupid in a particular area, like studies or common sense.
Can be combined with other words to specify the type of stupidity, e.g., 勉強馬鹿 (study-obsessed fool) or 馬鹿正直 (foolishly honest).
彼は勉強馬鹿だ。
He's a book-smart fool with no common sense.
A dated, playful insult meaning 'dunce' or 'blockhead'. Often used in old manga or by older generations.
Words like 馬鹿 and 阿呆 can be playful among close friends, but using them with strangers or superiors is extremely rude. Harsher words like クズ are fighting words. When in doubt, avoid direct insults.
馬鹿 is standard Japanese and used nationwide. 阿呆 is strongly associated with the Kansai region (Osaka, Kyoto, etc.) and often sounds more playful or dialectal. In Kansai, 阿呆 can be lighter than 馬鹿, while in Tokyo, 阿呆 may sound harsher or old-fashioned.
馬鹿 is very productive. You can attach it to nouns or adjectives to mean 'foolishly X' or 'obsessed with X'. For example, 馬鹿力 (ばかぢから) means 'stupid strength' (brute force), and 馬鹿笑い (ばかわらい) means 'guffawing'.
彼女は天然で面白い。
She's naturally funny (in an airheaded way).
低能は黙ってろ。
Shut up, you moron.
He's slow, so wait for him.
このおたんこなすが！
You blockhead!