Definition from Wiktionary, the free dictionary
See also Annihilation
annihilation (plural annihilations)
- The act of reducing to nothing, or nonexistence; or the act of destroying the form or combination of parts under which a thing exists, so that the name can no longer be applied to it; as, the annihilation of a corporation.
- The state of being annihilated.
- (physics) The process of a particle and its corresponding antiparticle combining to produce energy.
Related terms 
act of reducing to nothing
state of being annihilated
process of a particle and its corresponding antiparticle combining to produce energy