the state of being annihilated; extinction; destruction.
3.
Physics.
a.
Also called pair annihilation.the process in which a particle and antiparticle unite, annihilate each other, and produce one or more photons. Compare positronium.
b.
the conversion of rest mass into energy in the form of electromagnetic radiation.
Origin: 1630–40; (< F) < LL annihilātiōn- (s. of annihilātiō). See annihilate, -ion
[uh-nahy-uh-ley-shuh
n] 