rye·grass or rye grass  (rī'grās')  n. See darnel. [Alteration of raygrass : ray, darnel (from Middle English rai, perhaps alteration of Old French ivraie, from Latin ēbriāca, from feminine of ēbriācus, drunk (from the plant's effects if ingested), from ēbrius; see inebriate) + grass.] |