expression, noun
fault; flaw; weak point; shortcoming
Almost always used in the negative pattern 非の打ち所がない, meaning 'flawless' or 'nothing to criticize'. The standalone noun use is rare.
See also: 非の打ち所がない
彼の仕事ぶりは非の打ち所がない。
His work is flawless.
この計画には非の打ち所がないように見える。
This plan seems to have no flaws.
欠点 is a common, standalone noun for 'fault' or 'defect'. 非の打ち所 is a set phrase used almost exclusively in the negative pattern 非の打ち所がない.
Literally 'a place to strike a fault'. 非 means 'fault' or 'wrong', 打ち所 means 'a place to hit/strike'. The phrase originates from the idea of finding a point to criticize.