1. (noun)dog grass, couch grass, quackgrass, quack grass, quick grass, witch grass, witchgrass, Agropyron repens European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed Synonyms: old witch grass, couch grass, quick grass, tumble grass, quackgrass, quack grass, witch grass, dog grass, old witchgrass, witchgrass