[vir-ee-oh] 
| any of several small, insectivorous American birds of the family Vireonidae, having the plumage usually olive-green or gray above and white or yellow below. |
| vir·e·o (vîr'ē-ō') n. pl. vir·e·os Any of various small insect-eating New World songbirds of the genus Vireo, having grayish or greenish plumage. [Latin vireō, a kind of bird, from virēre, to be green.] |
