⌂ any of several weedy annual grasses (genus Digitaria) which spread rapidly because of their freely rooting stems, becoming a pest in lawns and gardens
also written crab grass
Origin of crabgrasscrab + grass: so named from fancied resemblance of the creeping stems to the legs of a crab
or crab grass
Any of certain annual grasses of the genus Digitaria, having prostrate stems that root at the nodes and widely naturalized in North America as weeds in lawns and agricultural fields.
(countable and uncountable, plural crabgrasses)