The loss of an entire animal species is referred to as

Extinction is the complete and permanent loss of an entire animal species from the earth.

Distinction means a mark of difference or honour and has nothing to do with species loss.

Annihilation means total destruction in general and is not the biological term for species loss.

Genocide refers to the deliberate mass killing of a human group, not the loss of an animal species.

Extinction occurs when the last individual of a species dies with no living descendants.

Habitat destruction, overhunting and climate change are leading drivers of extinction.