crab.grass HkrAb7grB:s, $-grAs n [U] Am a type of WEED (=wild plant which grows in a place where it is not wanted and prevents cultivated plants from growing freely) 马唐（破坏草地的一种野草） The crabgrass has started to take over our front lawn! 马唐草开始长满了我们的前院草地!