Source : Webster's Revised Unabridged Dictionary (1913)

Extinction \Ex*tinc"tion\, n. [L. extinctio, exstinction: cf. F.
   extinction.]
   1. The act of extinguishing or making extinct; a putting an
      end to; the act of putting out or destroying light, fire,
      life, activity, influence, etc.

   2. State of being extinguished or of ceasing to be;
      destruction; suppression; as, the extinction of life, of a
      family, of a quarrel, of claim.

Source : WordNet®

extinction
     n 1: no longer in existence; "the extinction of a species" [syn:
          {defunctness}]
     2: no longer active; extinguished; "the extinction of the
        volcano"
     3: the reduction of the intensity of radiation as a consequence
        of absorption and radiation
     4: complete annihilation; "they think a meteor cause the
        extinction of the dinosaurs" [syn: {extermination}]
     5: a conditioning process in which the reinforcer is removed
        and a conditioned response becomes independent of the
        conditioned stimulus [syn: {experimental extinction}]
     6: the act of extinguishing; causing to stop burning; "the
        extinction of the lights" [syn: {extinguishing}, {quenching}]