complain, cavil, grumble, moan, grouse, grouch, whine, bleat, quibble, niggle, nag;
find fault with, criticize, pick on, censure, denounce, condemn, decry, disparage
informal gripe, beef, bellyache, bitch, whinge, nitpick, pick holes, split hairs, sound off, kick up a fuss, knock
British informal chunter, create, be on at someone
Northern English informal mither
North American informal kvetch
complaining, cavilling, grumbling, moaning, grousing, grouching, grouchy, whining, bleating, fault-finding, quibbling, niggling, captious, nagging;
critical, criticizing, censorious, condemnatory, disparaging, scathing, slighting, reproachful, deprecatory, hypercritical, overcritical, pedantic, hard/difficult/impossible to please;
Scottish & Irish pass-remarkable
informal griping, bellyaching, bitching, whingeing, nitpicking, hair-splitting, picky
British informal chuntering
Northern English informal mithering
North American informal kvetching