If you call someone persnickety, you mean they fuss too much over tiny details that most people would let go — and you are not being kind. You are a little tired of it. A persnickety eater sends the soup back because of one speck. A persnickety neighbour complains about a picture hanging a little crooked. The word sits close to fussy and picky, but it carries a sharper edge: you think they should drop it. It is informal, more American; in Britain people often say pernickety instead, same idea. You hear it more from older speakers. Though actually, some people wear it with a small smile, as if being persnickety about their work is a kind of pride. Still, when you say it about someone else, it usually shows disapproval.

挑剔、吹毛求疵（帶點不以為然；美式口語，英式常說 pernickety）