barnyard grass

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

• noun Any of certain grasses in the genus Echinochloa, especially the annual species E. crus-galli, used sometimes for forage and widespread as a weed.

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

• noun a coarse annual panic grass; a cosmopolitan weed; occasionally used for hay or grazing