Cannibalism is the act or practice of humans eating the flesh or internal organs of other human beings. It is also called anthropophagy. A person who practices cannibalism is called a cannibal. The expression "cannibalism" has been extended into zoology to mean one individual of a species consuming all or part of another individual of the same species as food, including sexual cannibalism.
Furthermore, I would have to put a hot one into your brainpan if I caught you chowin' down on a zombie. BECAUSE YOU WOULD BECOME A ZOMBIE TOO!
Yes. A zombie is a human that is either possessed or infected by something, in most fiction I've seen anyway. It's still cannibalism if you eat a person with rabies, or a mental disorder - same if you eat a corpse.
I think the real question, does eating a zombie make you a zombie?
Eeeewwww... Of course it would. And again, eeeeewwwww... Why would anyone ever even think of doing that?
That depends. If you eat a corpse, are you a cannibal?
My exact thought
If the corpse is human, then yes. That is the definition of cannibal right there.