giant foxtail
nounDefinition of giant foxtail
: either of two coarse annual foxtails of the genus Setaria that are naturalized weeds in parts of the U.S.:
a
: an Asiatic foxtail (S. faberii) widely established in the eastern U.S.
b
: a West Indian foxtail (S. magna) established chiefly in the southeastern and southern U.S.