So vague the word can have alternate meanings in different languages. For example, in German it can mean "idiot."
WiiAssassin is right though. The term zombie is originally from voodoo culture. Scary thing is it's something real in voodoo culture. It was a curse of sort. Someone would mix up this bad cocktail of some crazy crap, only ingredients I remember are chicken bones and a certain type of blowfish, put it in someones food and if they eat the stuff they pretty much go into a coma. Their heartbeat lowers so much that most are pronounced dead in this state. They wake up days later moving but almost brain-dead, usually only doing anything if told to. People would do this as a form of slavery. Even the first zombie movie ever, White Zombie, was pretty much that.
I consider the Los Plagas infested to be zombies, cause pretty much what I just explained sounds closer to the Las Plagas than the virus living dead type. So if you look at it that way the Las Plagas infested people are more zombie-like than the modern concept of zombie.