Noun
1. no longer in existence;
"the extinction of a species"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 no longer active; extinguished;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"5. a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulus
6. the act of extinguishing; causing to stop burning;
"the extinction of the lights"