Source : Webster's Revised Unabridged Dictionary (1913)

Locust \Lo"cust\, n. [L. locusta locust, grasshopper. Cf.
   {Lobster}.]
   1. (Zo["o]l.) Any one of numerous species of long-winged,
      migratory, orthopterous insects, of the family
      {Acridid[ae]}, allied to the grasshoppers; esp.,
      ({Edipoda, or Pachytylus, migratoria}, and {Acridium
      perigrinum}, of Southern Europe, Asia, and Africa. In the
      United States the related species with similar habits are
      usually called {grasshoppers}. See {Grasshopper}.

   Note: These insects are at times so numerous in Africa and
         the south of Asia as to devour every green thing; and
         when they migrate, they fly in an immense cloud. In the
         United States the harvest flies are improperly called
         locusts. See {Cicada}.

   {Locust beetle} (Zo["o]l.), a longicorn beetle ({Cyllene
      robini[ae]}), which, in the larval state, bores holes in
      the wood of the locust tree. Its color is brownish black,
      barred with yellow. Called also {locust borer}.

   {Locust bird} (Zo["o]l.) the rose-colored starling or pastor
      of India. See {Pastor}.

   {Locust hunter} (Zo["o]l.), an African bird; the beefeater.

   2. [Etymol. uncertain.] (Bot.) The locust tree. See {Locust
      Tree} (definition, note, and phrases).

   {Locust bean} (Bot.), a commercial name for the sweet pod of
      the carob tree.

Source : WordNet®

locust bean
     n : long pod containing small beans and sweetish edible pulp;
         used as animal feed and source of a chocolate substitute
         [syn: {carob}, {carob bean}, {algarroba bean}, {algarroba},
          {locust pod}]