n]
| 1. | the act of extinguishing. |
| 2. | the fact or condition of being extinguished or extinct. |
| 3. | suppression; abolition; annihilation: the extinction of an army. |
| 4. | Biology. the act or process of becoming extinct; a coming to an end or dying out: the extinction of a species. |
| 5. | Psychology. the reduction or loss of a conditioned response as a result of the absence or withdrawal of reinforcement. |
| 6. | Astronomy. the diminution in the intensity of starlight caused by absorption as it passes through the earth's atmosphere or through interstellar dust. |
| 7. | Crystallography, Optics. the darkness that results from rotation of a thin section to an angle (extinction angle) at which plane-polarized light is absorbed by the polarizer. |
The disappearance of a species from the Earth.
Note: The fossil record tells us that 99.9 percent of all species that ever lived are now extinct.
extinction ex·tinc·tion (ĭk-stĭngk'shən)
n.
Progressive reduction in the strength of the conditioned response in successive conditioning trials during which only the conditioned stimulus is presented and the unconditioned stimulus is omitted. See absorbance.