From The Collaborative International Dictionary of English v.0.48 :
Rocket \Rock"et\, n. [F. roquette (cf. Sp. ruqueta, It ruchetta), fr. L. eruca.] (Bot.) (a) A cruciferous plant ({Eruca sativa) sometimes eaten in Europe as a salad. (b) Damewort. (c) Rocket larkspur. See below. [1913 Webster] Dyer's Rocket. (Bot.) See Dyer's broom, under Broom. Rocket larkspur (Bot.), an annual plant with showy flowers in long racemes ({Delphinium Ajacis). Sea rocket (Bot.), either of two fleshy cruciferous plants ({Cakile maritima and Cakile Americana) found on the seashore of Europe and America. Yellow rocket (Bot.), a common cruciferous weed with yellow flowers ({Barbarea vulgaris). [1913 Webster]