aves

‖n. pl. [ L., pl. of avis bird. ] (Zool.) The class of Vertebrata that includes the birds. [ 1913 Webster ]

☞ Aves, or birds, have a complete double circulation, oviparous reproduction, front limbs peculiarly modified as wings; and they bear feathers. All existing birds have a horny beak, without teeth; but some Mesozoic fossil birds (Odontornithes) had conical teeth inserted in both jaws. The principal groups are: Carinatæ, including all existing flying birds; Ratitæ, including the ostrich and allies, the apteryx, and the extinct moas; Odontornithes, or fossil birds with teeth. [ 1913 Webster ]

The ordinary birds are classified largely by the structure of the beak and feet, which are in direct relation to their habits. See Beak, Bird, Odontonithes. [ 1913 Webster ]