an annual grass, Digitaria sanguinalis, common in cultivated and waste grounds and often occurring as a pest weed in lawns.
Origin of crab grass
First recorded in 1590–1600
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for crabgrass
Bluegrass (Poa pratensis) and crabgrass (Digitaria ischaemum) form most of the sod.
The walk up the "lawn" was flagstone with crabgrass between the stones.The Fourth R|George Oliver Smith
British Dictionary definitions for crabgrass
any of several coarse weedy grasses of the genus Digitaria, which grow in warm regions and tend to displace other grasses in lawns
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for crabgrass
Online Etymology Dictionary, © 2010 Douglas Harper