passerine

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

• adjective Of or relating to birds of the order Passeriformes, which have feet specialized for grasping branches and similar structures, with the first toe facing backward. The order includes the songbirds and certain other groups, such as the flycatchers of the Americas.
• noun A bird of the order Passeriformes.

from The Century Dictionary.

• Resembling or related to a sparrow; of or pertaining to the Passerinæ, in any sense, or the Passeres; passeriform.
• About as large as a sparrow: as, the passerine parrot, Psittacula passerina; the passerine ground-dove, Chamæpelia passerina; the passerine owl, Glaucidium passerinum. Also passeroid.
• noun A member of the Passerinæ, Passeres, or Passeriformes.

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

• adjective (Zoöl.) Of or pertaining to the Passeres.
• noun (Zoöl.) One of the Passeres.

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

• noun Any bird of the order Passeriformes, which comprises more than half of all bird species.
• adjective Of, or relating to a passerine or perching bird.

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

• adjective relating to or characteristic of the passeriform birds
• noun perching birds mostly small and living near the ground with feet having 4 toes arranged to allow for gripping the perch; most are songbirds; hatchlings are helpless