1. the act of extinguishing.
2. the condition of being extinguished.
3. the fact of being extinct or the process of becoming extinct: "the most effective agent in the extinction of species is the pressure of other species” ( Alfred R. Wallace).
4. psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld.
5. physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability.

1. the action of making or becoming extinct; annihilation.
2. the absorption or scattering of electromagnetic radiation emitted by astronomical objects by intervening dust and gas before it reaches the observer.

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.
3. the ceasing to exist of a species of living organism, such as a plant or animal, whose numbers declined to the point where the last member of the species died and therefore no new members of the species could ever again be born.

1. the act of extinguishing, or the state of being extinguished; a quenching or putting out, as of fire or flame.
2. hence A bringing or coming to an end; a putting out of existence; suppression; destruction.
3. in optics, the arresting of a beam of light by polarization, by the imperfect transparency of the medium, or otherwise.

1. the reduction of the intensity of radiation as a consequence of absorption and radiation
2. no longer active; extinguished
3. complete annihilation
4. no longer in existence
5. the act of extinguishing; causing to stop burning
6. a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulus