OXFORD DICTIONARY
, n. (pl. same) any freshwater fish of the family Cyprinidae, esp. Cyprinus carpio, often bred for use as food.
, v.intr. (usu. foll. by at) find fault; complain pettily.
carper n.
obs. ME senses 'talk, say, sing' f. ON karpa to brag: mod. sense (16th c.) from or infl. by L carpere pluck at, slander
THESAURUS
bug, bully, bullyrag,
carp at, catch at straws, cavil, complain, criticize, cut up, fault-find, find fault, fret at, fuss at, gripe, hassle, henpeck, knock, nag, nibble at, niggle, nitpick, peck at, pester, pettifog, pick at, pick holes, pick on, pick to pieces, pull apart, pull to pieces, quibble, take exception, tear apart, tear to pieces, yap at