Source : Webster's Revised Unabridged Dictionary (1913)

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 Cheiroptera, 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 {Cheiroptera} and {Vampire}.

   {Bat tick} (Zo["o]l.), a wingless, dipterous insect of the
      genus {Nycteribia}, parasitic on bats.