beak (redirected from bill)

beak

 or bill

Stiff, projecting oral structure of birds and turtles (both of which lack teeth) and certain other animals (e.g., cephalopods and some insects, fishes, and mammals). The term bill is preferred for the beak of a bird, which is composed of upper and lower jaws covered by a horny sheath of skin, with the nostrils on top, usually at the base. The shapes and sizes of bills are adapted for obtaining food, preening, building nests, and other functions; they range from the long, slim bills of nectar-sipping hummingbirds to the sturdy, curved, nut-cracking bills of parrots.