Collins COBUILD Advanced Learner's English Dictionary - nitpicking

also nit-picking If you refer to someone’s opinion as nitpicking, you disapprove of the fact that it concentrates on small and unimportant details, especially to try and find fault with something. A lot of nit-picking was going on about irrelevant things... I can get down to nitpicking detail, I am pretty fussy about certain things. = quibbling N-UNCOUNT c darkgreen]disapproval