Search Result for "antiparticle": 
Wordnet 3.0

NOUN (1)

1. a particle that has the same mass as another particle but has opposite values for its other properties; interaction of a particle and its antiparticle results in annihilation and the production of radiant energy; 



WordNet (r) 3.0 (2006):

antiparticle
    n 1: a particle that has the same mass as another particle but
         has opposite values for its other properties; interaction
         of a particle and its antiparticle results in annihilation
         and the production of radiant energy