Translation guide
The English word "dumb" has several distinct meanings. This guide covers the most common uses for learners: inability to speak, temporary speechlessness, and informal use meaning "stupid."
Describing a person who cannot speak due to a physical or medical condition.
A common, neutral phrase meaning 'unable to speak.' It literally means 'mouth cannot function.'
He became unable to speak after the accident.
A noun meaning 'mute person.' Can be considered blunt or outdated; use with care.
This term can be perceived as insensitive or archaic. Prefer descriptive phrases like 口がきけない in most situations.
He has been mute since birth.
Describing someone who is so shocked or surprised that they cannot speak.
Informal use meaning 'stupid' or 'foolish.'
The most common casual word for 'stupid' or 'idiot.' Can be used playfully or insultingly depending on tone.
Can be offensive if used aggressively. Use with close friends only.
Don't say such dumb things.
That guy is really dumb.
Similar to バカ, but more common in Kansai dialect. Often used jokingly.
Means 'stupid' or 'foolish,' with a nuance of being slow or dim-witted. Less harsh than バカ.
A more formal or literary word for 'foolish' or 'stupid.' Often used in writing or serious contexts.
In Japanese, directly calling someone 'dumb' (バカ, アホ) is very casual and can be highly offensive. In polite or formal situations, use softer expressions like あまり賢くない (not very smart) or rephrase entirely.
He is not very smart.
Both mean 'stupid' or 'idiot,' but バカ is standard Japanese while アホ is strongly associated with the Kansai region. In Kansai, アホ can be more playful, while バカ might sound harsher. In Tokyo, バカ is the default.
To be dumbfounded or taken aback, often with a nuance of being stunned into silence.
Everyone was dumbfounded by the sudden event.
I was speechless at his rude attitude.
Don't say dumb stuff.
He has a dumb look on his face.
That is a dumb decision.