Translation guide
The English word 'ass' has several distinct meanings: a donkey-like animal, buttocks (slang), a foolish person (slang), and vulgar sexual slang. This guide focuses on the most common meanings an English-speaking learner might need to express in Japanese, from the animal to informal body part references.
Referring to the animal, a domesticated member of the horse family, often used in idioms or literally.
The standard word for 'donkey' in Japanese. Used in everyday contexts, zoos, and children's stories.
あの農場にはロバがいます。
There is a donkey on that farm.
Kanji form of 'ロバ', rarely used in modern writing. Mostly seen in literary or historical contexts.
驢馬が荷物を運んでいた。
A donkey was carrying luggage.
Informal reference to the buttocks or rear end, often used in casual or vulgar contexts.
Polite and common word for 'buttocks' or 'bottom'. Suitable for most everyday situations, including with children.
転んでお尻を打った。
I fell and hit my butt.
More direct and slightly crude word for 'buttocks'. Used in casual speech among friends or in vulgar expressions.
あいつの尻を蹴ってやった。
I kicked that guy's ass.
Very informal and vulgar slang for 'ass'. Used mainly among close male friends or in rough speech. Can be offensive.
Avoid using in polite company or formal settings.
ケツが痛い。
My ass hurts.
Calling someone a stupid or annoying person, similar to 'idiot' or 'jerk'.
Common insult meaning 'idiot' or 'fool'. Equivalent to calling someone an 'ass' in a derogatory way.
あのバカがまたやった。
That ass did it again.
Kansai-dialect equivalent of 'バカ', often used playfully or as a mild insult. Can be used similarly to 'ass'.
何してんねん、アホ！
What are you doing, you ass!
Means 'blockhead' or 'dunce'. A bit old-fashioned but can be used to call someone an 'ass' in the sense of being clueless.
この間抜けが！
You ass!
Referring to sexual intercourse or related vulgar expressions (e.g., 'piece of ass').
Direct translations of vulgar sexual slang like 'ass' are rarely natural in Japanese. Instead, use context-appropriate euphemisms or rephrase entirely. For 'piece of ass' (attractive person), use terms like '美人' (beautiful woman) or 'イケメン' (handsome man).
彼女はすごい美人だ。
She's a real piece of ass. (lit. She's a great beauty.)
Loanword for 'sex'. Can be used in phrases like 'get some ass' but sounds direct and may be awkward. Often softened with verbs like 'やる' (to do) in slang.
Using 'セックス' directly can sound clinical or overly blunt. Native slang like 'やる' or '寝る' is more natural for casual sexual references.
昨日、彼女とやった。
I got some ass last night. (lit. I did it with my girlfriend.)
Directly translating 'ass' into Japanese as 'ロバ' (donkey) to insult someone will not be understood. Use established insults like 'バカ' or 'アホ' instead.
お前はロバだ！
You're an ass! (literal, not understood)
'お尻' is polite and safe for most situations. '尻' is more direct and casual, often used in set phrases or among friends. 'ケツ' is vulgar slang, similar to 'ass' in English, and should be used carefully.