noun
sharp person; clever and capable person
Describes someone who is mentally sharp, astute, and highly competent, often with a connotation of being shrewd or resourceful.
彼はなかなかの切れ者で、難しい交渉もまとめてしまう。
He is quite a sharp person, able to bring even difficult negotiations to a close.
あの新人は切れ者だと評判だ。
That new employee has a reputation for being sharp and capable.
Compound of 切れ (kire, 'sharpness, cutting ability') and 者 (mono, 'person'). The exact historical derivation is uncertain, but the word figuratively describes a person whose mind is as sharp as a blade.