Zombie

A zombie (plural: zombies - variably known as the undead or the living dead) is an animalistic organism that has been reanimated after death through regenesis.

Basically, zombies are animals, including humans, that DON'T STAY DEAD... their brain is sent into 'hibernation' but it still functions on a primitive level. Scientists are baffled by this biological phenomenom they're calling 'the vengeance.' 

Because zombies are the reduction of an animal to its most primal instincts, they are extremely dangerous. They are walking corpses, decaying from the inside. They hunt and feed on flesh in order to sustain their declining physiological structure. And I'm bored...