Aves \A"ves\, n. pl. [L., pl. of avis bird.] (Zo["o]l.) The class of Vertebrata that includes the birds. [1913 Webster] Note: 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: {Carinat[ae]}, including all existing flying birds; {Ratit[ae]}, including the ostrich and allies, the apteryx, and the extinct moas; {Odontornithes}, or fossil birds with teeth. [1913 Webster] Note: 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] ||