Any of several kinds of bristle grass (genus Setaria), which are serious arable weeds; especially yellow bristle grass, S. glauca, and green bristle grass, S. viridis.
Origin
Mid 19th century.
Definition of pigeon grass in US English:
pigeon grass
noun
US
Any of several kinds of bristle grass (genus Setaria), which are serious arable weeds; especially yellow bristle grass, S. glauca, and green bristle grass, S. viridis.