Bat \Bat\, n. [Corrupt. from OE. back, backe, balke; cf. Dan. aften-bakke (aften evening), Sw. natt-backa (natt night), Icel. le[eth]r-blaka (le[eth]r leather), Icel. blaka to flutter.] (Zo["o]l.) One of the {Chiroptera}, an order of flying mammals, in which the wings are formed by a membrane stretched between the elongated fingers, legs, and tail. The common bats are small and insectivorous. See {Chiroptera} and {Vampire}. [1913 Webster] Silent bats in drowsy clusters cling. --Goldsmith. [1913 Webster] {Bat tick} (Zo["o]l.), a wingless, dipterous insect of the genus {Nycteribia}, parasitic on bats. [1913 Webster] ||