The
beak,
bill, or
rostrum is an external anatomical structure of
birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young. The terms
beak and
rostrum are also used to refer to a similar mouthpart in some
Ornithischian dinosaurs,
monotremes,
cephalopods (see
Cephalopod beak),
cetaceans,
billfishes,
pufferfishes,
turtles,
Anuran tadpoles and
sirens.