adjective

characterized by or fond of small and overfine distinctions.

the legal experts have a particularly hair-splitting mentality

quibbling,fault-finding,niggling,cavilling,carping,captious,critical,criticizing,disapproving,censorious,judgemental,overcritical,hypercritical,pedantic,punctilious,pettifogging,pass-remarkable,nitpicking,picky,pernickety,persnickety,nice,overnice

noun

the action of making small and overfine distinctions; quibbling.