Also called 'beak' or 'rostrum'. Name for the projecting jaws of a bird with their horny sheaths (see picture under 'bird topography'). The jaws consist of the upper mandible or maxilla and the lower mandible. The whole horny structure is known as rhampotheca; the upper and lower parts as rhinotheca and gnathotheca resp. The main function is the grasping of food, but it doesn't have true teeth, although some groups of birds have saw-toothed edges (serrations) composed of a horny substance on their bill (e.g. ducks). Many different forms and types exist as a adaptation to feeding habits.

Alternative forms for bill : beak, billed, bills, rostrum.