The Collaborative International Dictionary of English v.0.48:

Swallow \Swal"low\, n. [OE. swalowe, AS. swalewe, swealwe; akin
   to D. zwaluw, OHG. swalawa, G. schwalbe, Icel. & Sw. svala,
   Dan. svale.]
   1. (Zool.) Any one of numerous species of passerine birds of
      the family Hirundinidae, especially one of those species
      in which the tail is deeply forked. They have long,
      pointed wings, and are noted for the swiftness and
      gracefulness of their flight.
      [1913 Webster]

   Note: The most common North American species are the barn
         swallow (see under Barn), the cliff, or eaves,
         swallow (see under Cliff), the white-bellied, or
         tree, swallow (Tachycineta bicolor), and the bank
         swallow (see under Bank). The common European swallow
         (Chelidon rustica), and the window swallow, or martin
         (Chelidon urbica), are familiar species.
         [1913 Webster]

   2. (Zool.) Any one of numerous species of swifts which
      resemble the true swallows in form and habits, as the
      common American chimney swallow, or swift.
      [1913 Webster]

   3. (Naut.) The aperture in a block through which the rope
      reeves. --Ham. Nav. Encyc.
      [1913 Webster]

   Swallow plover (Zool.), any one of several species of
      fork-tailed ploverlike birds of the genus Glareola, as
      Glareola orientalis of India; a pratincole.

   Swallow shrike (Zool.), any one of several species of East
      Indian and Asiatic birds of the family Artamiidae,
      allied to the shrikes but similar to swallows in
      appearance and habits. The ashy swallow shrike (Artamus
      fuscus) is common in India.

   Swallow warbler (Zool.), any one of numerous species of
      East Indian and Australian singing birds of the genus
      Dicaeum. They are allied to the honeysuckers.
      [1913 Webster]