Translation guide
Describes someone who is slow to understand, not very intelligent, or lacking sharpness of mind. Japanese has many nuanced words for this, ranging from mild to harsh.
To describe someone who takes time to grasp things or is generally not quick-thinking.
To bluntly state that someone is not smart, often in a derogatory way.
The most common word for 'stupid' or 'fool'. Can be used jokingly or offensively depending on context.
To describe someone who is not intellectually disabled but is a bit slow or simple, often in a softer or euphemistic way.
Refers to a slowpoke or dimwit; implies both mental and physical slowness. Mildly derogatory.
Many Japanese words for 'dim-witted' are insulting. Use with caution, especially 馬鹿, アホ, and 間抜け. In polite conversation, it's better to describe the behavior rather than label the person.
彼は少し理解が遅いですね。
He is a bit slow to understand, isn't he? (more polite)
Literally 'dull', used for both physical and mental slowness. Common and versatile.
彼は頭の回転が鈍い。
He is slow on the uptake.
Colloquial and slightly derogatory; implies sluggishness or dim-wittedness in action or thought.
あいつはとろいから、説明しても無駄だ。
That guy is so dim-witted, explaining is pointless.
Means 'stupid' or 'dim-witted' with a nuance of being foolish or missing the obvious. Can be insulting.
そんな間抜けなミスをするなんて。
Making such a dim-witted mistake.
Formal and literary term for 'stupid' or 'dim-witted'. Rare in everyday speech.
彼は愚鈍な男だ。
He is a dim-witted man.
馬鹿なことを言うな。
Don't say such dim-witted things.
Kansai dialect equivalent of 馬鹿, but widely understood. Often used playfully.
お前、アホやなあ。
You're so dim-witted.
Means 'low intelligence' or 'feeble-minded'. Harsh and often used in insults.
低能な奴だ。
He's a dim-witted fellow.
彼はのろまだから、急かさないで。
He's a bit dim-witted, so don't rush him.
Similar to のろま but slightly stronger; emphasizes stupidity and slowness.
うすのろな行動に呆れる。
I'm amazed at his dim-witted behavior.
Means 'absent-minded' or 'vague', but can imply dim-wittedness when describing a person's nature.
彼はぼんやりしていて、話が通じない。
He's so dim-witted that you can't get through to him.