Any of several kinds of couch grass, specifically common couch, Elymus repens, and the closely related E. caninus, reputed to be eaten by dogs to produce vomiting. Now chiefly North American.
Late 16th century; earliest use found in John Gerard (c1545–1612), herbalist. In some forms from the genitive of dog + grass; in some forms from dog + grass; compare post-classical Latin gramen caninum, scientific Latin Triticium caninum (LinnaeusSpecies plantarum I. 86).