Etymology: Probably either (i) < an unattested variant or alteration of Anglo-Norman yverai and Middle French ivraye darnel, ryegrass (see ray n.⁴ and ivray n.), or perhaps (ii) < an unattested derivative of Anglo-Norman and Old French, Middle French ivre drunk (see yveresce n.); the plant ultimately being so called because it was thought to induce drunkenness (compare drunken rye-grass n. at drunken adj. Compounds 2). Compare ray n.⁴ and later ivray n.The French word may have been transmitted via an unattested Middle Cornish word (compare Cornish ivre ryegrass, darnel (1707), although this could itself be either of French or English origin); compare Welsh efrau , efre , efr (collective noun) ryegrass, darnel (15th cent.; < either French or English). J. Trevisa (compare quot. a1425) came from a Cornish family. Compare also Welsh English (Pembrokeshire) ever ergot of rye (1977). With ever-grass in quot. 1863 compare ray-grass n. and ryegrass n.² Variant forms. The origin of every at β. forms is unclear; it has been suggested that it reflects an earlier form of the word, preserving the final syllable of the etymon; N.E.D. (1891) records this in a separate entry and gives the pronunciation as (ˈɛvərɪ, ˈɛvrɪ). It has further been suggested that the abbreviated Middle English form eur' at α. forms may also reflect this type. Some forms perhaps reflect later association with hay n.¹ or haver n.²

Etymology: Origin unknown.