bluebird

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several North American songbirds of the genus Sialia, having blue plumage and usually a rust-colored breast in the male.

from The Century Dictionary.

• noun An American oscine passerine bird, of the genus Sialia, of which blue is the chief color.
• noun Some other bird of a blue color: as, the fairy bluebird of Java, Irene turcosa.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A small song bird (Sialia sialis), very common in the United States, and, in the north, one of the earliest to arrive in spring. The male is blue, with the breast reddish. It is related to the European robin.
• noun (Zoöl.) a brilliant Indian or East Indian bird of the genus Irena, of several species.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various North American birds of the genus Sialia in the thrush family. Their plumage is blue or blue and red.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun fruit-eating mostly brilliant blue songbird of the East Indies
• noun blue North American songbird