The Collaborative International Dictionary of English v.0.48:

Mung \Mung\ (m[u^]ng), n. [Hind. m[=u]ng.] (Bot.)
   Green gram, a kind of legume (pulse) (Vigna radiata syn.
   Phaseolus aureus, syn. Phaseolus Mungo), grown for food
   in British India; called also gram, mung bean, Chinese
   mung bean, and green-seeded mung bean. It is an erect,
   bushy annual producing edible green or yellow seeds, and
   edible pods and young sprouts. --Balfour (Cyc. of India).
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mung bean \Mung" bean`\ (m[u^]ng" b[=e]n`), n.
   The mung (Vigna radiata).
   [PJC]

   2. The bean produced by the mung.
      [PJC]

WordNet (r) 3.0 (2006):

mung bean
    n 1: erect bushy annual widely cultivated in warm regions of
         India and Indonesia and United States for forage and
         especially its edible seeds; chief source of bean sprouts
         used in Chinese cookery; sometimes placed in genus
         Phaseolus [syn: mung, mung bean, green gram, golden
         gram, Vigna radiata, Phaseolus aureus]