The primary definition of a zombie, according to Google is as follows:

a corpse said to be revived by witchcraft, esp. in certain African and Caribbean religions.

Early religions lacked the scientific methods to explain everyday events and defaulted to labeling things that couldn’t otherwise be explained as witchcraft.

It is through that stretch of the definition of a zombie that allow the walkers on AMC’s The Walking Dead to be labeled zombies. Even though we know the walkers to be infected by a virus that seems to be fairly predictable, the same behavior in another culture would have been seen as witchcraft.

Now to Frankenstein(’s monster), while he was way ahead of the zombie craze, he still qualifies as one even though he was electrically resurrected from an assortment of bodies and did not feed on brains.