The Collaborative International Dictionary of English v.0.48:

Pigeon \Pi"geon\, n. [F., fr. L. pipio a young pipping or
   chirping bird, fr. pipire to peep, chirp. Cf. Peep to
   chirp.]
   1. (Zool.) Any bird of the order Columb[ae], of which
      numerous species occur in nearly all parts of the world.
      [1913 Webster]

   Note: The common domestic pigeon, or dove, was derived from
         the Old World rock pigeon or rock dove (Columba
         livia), common in cities. It has given rise to
         numerous very remarkable varieties, such as the
         carrier, fantail, nun, pouter, tumbler, etc. The common
         wild pigeon of the Eastern United States is the
         Mourning dove (Zenaida macroura, called also
         Carolina dove). Before the 19th century, the most
         common pigeon was the passenger pigeon, but that
         species is now extinct. See Passenger pigeon, and
         Carolina dove under Dove. See, also, Fruit
         pigeon, Ground pigeon, Queen pigeon, Stock
         pigeon, under Fruit, Ground, etc.
         [1913 Webster +PJC]

   2. An unsuspected victim of sharpers; a gull. [Slang]
      [1913 Webster]

   Blue pigeon (Zool.), an Australian passerine bird
      (Graucalus melanops); -- called also black-faced crow.


   Green pigeon (Zool.), any one of numerous species of Old
      World pigeons belonging to the family Treronid[ae].

   Imperial pigeon (Zool.), any one of the large Asiatic fruit
      pigeons of the genus Carpophada.

   Pigeon berry (Bot.), the purplish black fruit of the
      pokeweed; also, the plant itself. See Pokeweed.

   Pigeon English [perhaps a corruption of business English],
      an extraordinary and grotesque dialect, employed in the
      commercial cities of China, as the medium of communication
      between foreign merchants and the Chinese. Its base is
      English, with a mixture of Portuguese and Hindustani.
      --Johnson's Cyc.

   Pigeon grass (Bot.), a kind of foxtail grass (Setaria
      glauca), of some value as fodder. The seeds are eagerly
      eaten by pigeons and other birds.

   Pigeon hawk. (Zool.)
      (a) A small American falcon (Falco columbarius). The
          adult male is dark slate-blue above, streaked with
          black on the back; beneath, whitish or buff, streaked
          with brown. The tail is banded.
      (b) The American sharp-shinned hawk (Accipiter velox or
          Accipiter fuscus).

   Pigeon hole.
      (a) A hole for pigeons to enter a pigeon house.
      (b) See Pigeonhole.
      (c) pl. An old English game, in which balls were rolled
          through little arches. --Halliwell.

   Pigeon house, a dovecote.

   Pigeon pea (Bot.), the seed of Cajanus Indicus; a kind of
      pulse used for food in the East and West Indies; also, the
      plant itself.

   Pigeon plum (Bot.), the edible drupes of two West African
      species of Chrysobalanus (Chrysobalanus ellipticus and
      Chrysobalanus luteus).

   Pigeon tremex. (Zool.) See under Tremex.

   Pigeon wood (Bot.), a name in the West Indies for the wood
      of several very different kinds of trees, species of
      Dipholis, Diospyros, and Coccoloba.

   Pigeon woodpecker (Zool.), the flicker.

   Prairie pigeon. (Zool.)
      (a) The upland plover.
      (b) The golden plover. [Local, U.S.]
          [1913 Webster]