Any one of numerous species of American singing birds belonging to Vireo
and allied genera of the family Vireonidæ
. In many of the species the back is greenish, or olive-colored. Called also greenlet
. [1913 Webster
" In the Eastern United States the most common species are the white-eyed vireo (Vireo Noveboracensis), the red-eyed vireo (Vireo olivaceus), the blue-headed, or solitary, vireo (Vireo solitarius), the warbling vireo (Vireo gilvus), and the yellow-throated vireo (Vireo flavifrons). All these are noted for the sweetness of their songs."