Translation guide
A person who acts as if they know everything, often in an annoying way. Japanese has several colorful terms for this, ranging from mild to harsh.
Describing someone who behaves as if they have all the answers, often in an irritating manner.
A common term for someone who pretends to know something they don't, or acts like a know-it-all. Can be used as a noun or suru-verb.
彼はいつも知ったかぶりをする。
He always acts like a know-it-all.
知ったかぶりな態度が嫌われる。
A know-it-all attitude is disliked.
Literally 'knowledgeable face', used to describe someone who has a know-it-all expression or manner. Often implies they are showing off their knowledge.
彼は物知り顔で説明した。
He explained with a know-it-all look.
Similar to 知ったかぶり, but slightly more literary or old-fashioned. Means acting as if one knows.
知った風な口をきくな。
Don't talk like you know everything.
Referring to someone who genuinely possesses extensive knowledge, but may be perceived as a know-it-all.
A person of extensive knowledge; a polymath. Can be neutral or slightly negative depending on context.
彼は博識家だが、少し自慢げだ。
He's a know-all, but a bit boastful.
A knowledgeable person. Often used positively, but can imply a know-it-all when used sarcastically or with certain modifiers.
彼は本当に物知りだね。
He really is a know-all, isn't he?
あの物知りがまた講釈を始めた。
That know-all has started lecturing again.
Literally 'living dictionary', a person who knows everything about a subject. Can be used for a know-all in a specific domain.
Strongly negative words for an obnoxious person who flaunts their knowledge.
A rude way to call someone a know-it-all. Combines 知ったかぶり with 野郎 (bastard).
Very informal and insulting. Use only among close friends or in heated arguments.
あの知ったかぶり野郎がまたでしゃばった。
That know-it-all jerk butted in again.
Shortened slang for 知ったかぶり. Used mostly in casual conversation.
あいつ、マジ知ったかだよな。
That guy is such a know-all, seriously.
知ったかぶり implies pretending to know, while 物知り means actually knowledgeable. However, 物知り can be used sarcastically to mean know-it-all. Context and tone determine the nuance.
彼は物知りだ（褒め言葉）。
He is knowledgeable (compliment).
彼は物知りだ（皮肉）。
He's a know-it-all (sarcastic).
The English 'know-all' doesn't have a single direct equivalent. Translating it as 全てを知っている人 would sound unnatural. Use the terms above based on the nuance you want to convey.
彼はこの町の生き字引だ。
He's the know-all of this town.