Definition of "extinction" []

• The act of extinguishing. (noun)
• The condition of being extinguished. (noun)
• 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). (noun)
• Psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld. (noun)
• Physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• ""The term extinction is generally used to describe new learning that the previously feared event is now safe," Phelps tells WebMD."
• "Voluntary human extinction is the humanitarian alternative to human disasters."
• "As compared to the neutral mutant, this probability of extinction is less by only 0.01."