The termination of any lineage of organisms, from subspecies to species and higher taxonomic categories from genera to phyla Extinction can be local, in which one or more populations of a species or other unit vanish but others survive elsewhere, or total (global), in which all the populations vanish When biologists speak of the extinction of a particular species without further qualification, they mean total extinction1
a conditioning process in which the reinforcer is removed and a conditioned response becomes independent of the conditioned stimulus complete annihilation; "they think a meteor cause the extinction of the dinosaurs"