\Vir"e*o\, n. [L., a species of bird.] (Zo["o]l.)
Any one of numerous species of American singing birds
belonging to {Vireo} and allied genera of the family
{Vireonid[ae]}. In many of the species the back is greenish,
or olive-colored. Called also {greenlet}.
Note: In the Eastern United States the most common species
      are the white-eyed vireo ({Vireo Noveboracensis}), the
      redeyed vireo ({V. olivaceus}), the blue-headed, or
      solitary, vireo ({V. solitarius}), the warbling vireo
      ({V. gilvus}), and the yellow-throated vireo ({V.
      flavifrons}). All these are noted for the sweetness of
      their songs.