noun
well-informed person; walking encyclopedia; extensive knowledge
Refers to a person who knows a lot about many things, or the quality of having broad knowledge. Often used in phrases like 物知り顔 (knowing look) or 物知りぶる (to act like a know-it-all).
彼は本当に物知りで、どんな質問にも答えてくれる。
He is really knowledgeable and answers any question.
祖父は植物に詳しい物知りだ。
My grandfather is a walking encyclopedia when it comes to plants.