The Collaborative International Dictionary of English v.0.48:

Passeriformes \Passeriformes\ prop. n.
   The largest order of birds comprising about half the known
   species: rooks; finches; sparrows; tits; warblers; robins;
   wrens; swallows; etc.; in four suborders: Eurylaimi; Tyranni;
   Menurae; Oscines or Passeres.

   Syn: order Passeriformes.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Passeriformes
    n 1: largest order of birds comprising about half the known
         species; rooks; finches; sparrows; tits; warblers; robins;
         wrens; swallows; etc.; the four suborders are Eurylaimi and
         Tyranni and Menurae and Oscines or Passeres [syn:
         Passeriformes, order Passeriformes]