Source : Webster's Revised Unabridged Dictionary (1913)

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.

   {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 {C. Americana}) found on the
      seashore of Europe and America.

   {Yellow rocket} (Bot.), a common cruciferous weed with yellow
      flowers ({Barbarea vulgaris}).

Source : WordNet®

Delphinium ajacis
     n : commonly cultivated larkspur of southern Europe having
         unbranched spikelike racemes of blue or sometimes
         purplish or pinkish flowers; sometime placed in genus
         Delphinium [syn: {rocket larkspur}, {Consolida ambigua}]