Peck at is an idiomatic word that means "to nibble or strike something repeatedly with a beak or bill." It is often used to describe birds' behavior while picking their food. There are several synonyms for the word "peck at," including nibble, gnaw, bite, munch, graze, pick, pluck, chisel, and snap. Nibble means to take small bites or nibbles of something. Gnaw means to chew something persistently. Bite means to take a whole bite of something. Munch means to chew something noisily. Graze means to nibble on grass or similar vegetation. Pick means to select something carefully. Pluck means to pull something out with one's fingers or beak. Chisel means to cut something with a chisel tool. Finally, snap means to take a sudden bite of something.