Antiparticle

['æntɪ,pɑːtɪk(ə)l] or ['æntɪpɑrtɪkl]

Definition

(noun.) 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.

Typist: Oliver--From WordNet