From The Collaborative International Dictionary of English v.0.48 :
meadowlark \meadowlark\, meadow lark \meadow lark\n. (Zool.),
Any species of Sturnella, a genus of North American
songbirds allied to the starlings. The common species
({Sturnella magna) has a yellow breast with a black
crescent.
Syn: lark.
[1913 Webster + WordNet 1.5] Meadowsweet
From WordNet (r) 3.0 (2006) :
meadowlark
n 1: North American songbirds having a yellow breast [syn:
meadowlark, lark]