From The Collaborative International Dictionary of English v.0.48:
Rye \Rye\ (r[imac]), n. [OE. rie, reie, AS. ryge; akin to Icel. rugr, Sw. r[*a]g, Dan. rug, D. rogge, OHG. rocco, roggo, G. rocken, roggen, Lith. rugei, Russ. roje, and perh. to Gr. 'o`ryza rice. Cf. Rice.] 1. (Bot.) A grain yielded by a hardy cereal grass (Secale cereale), closely allied to wheat; also, the plant itself. Rye constitutes a large portion of the breadstuff used by man. [1913 Webster]
2. A disease in a hawk. --Ainsworth. [1913 Webster]
Rye grass, Italian rye grass, (Bot.) See under Grass. See also Ray grass, and Darnel.
Wild rye (Bot.), any plant of the genus Elymus, tall grasses with much the appearance of rye. [1913 Webster]