The Collaborative International Dictionary of English v.0.48:

horsebean \horsebean\ n.
   1. The seed of the broad-bean plant.

   Syn: broad bean, fava bean.
        [WordNet 1.5]

   2. A large shrub or shrubby tree (Parkinsonia aculeata)
      having sharp spines and pinnate leaves with small
      deciduous leaflets and sweet-scented racemose
      yellow-orange flowers; grown as ornamentals or hedging or
      emergency food for livestock; originating in tropical
      America but naturalized in the Southern U. S.

   Syn: Jerusalem thorn, Parkinsonia aculeata.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

horsebean
    n 1: seed of the broad-bean plant [syn: broad bean, fava
         bean, horsebean]
    2: large shrub or shrubby tree having sharp spines and pinnate
       leaves with small deciduous leaflets and sweet-scented
       racemose yellow-orange flowers; grown as ornamentals or
       hedging or emergency food for livestock; tropical America but
       naturalized in southern United States [syn: Jerusalem
       thorn, horsebean, Parkinsonia aculeata]