Pronunciation: (nig'ul),[key] —v.i.,-gled, -gling. 1. to criticize, esp. constantly or repeatedly, in a peevish or petty way; carp: to niggle about the fine points of interpretation; preferring to niggle rather than take steps to correct a situation. 2. to spend too much time and effort on inconsequential details: It's difficult to be meticulous and not niggle. 3. to work ineffectively; trifle: to niggle with an uninteresting task.