Extinction is when all members of a particular group die. Most often, we use it to discuss animal species. Many fear that the tiger is headed for extinction because of development and hunting.
People are still trying to figure out what caused the extinction of the dinosaurs: many think it was because of an asteroid. When people cut down rain forests, it can lead to the extinction of many species. Although extinction can be natural or unintended, the word can also mean forced, planned killing. Many people refer to the Holocaust as Hitler's attempt to bring about the extinction of the Jews. Languages also face extinction when no one speaks them anymore.