I thought the definition of a zombie was someone who continued to live once all organs/vital life signs had completely shut down or whatever, which I believe is pretty much impossible. Now if you mean some kind of rabies-like disease that makes people want to eat brains, then sure. Although it'd probably be less eating brains and more just eating raw meat (Including humans, but also other animals) period.
No, that does not make people who have been resuscitated by CPR or by whatever those shocky thingys that doctors apparantly shout "CLEAR" while using them, zombies, because that gives the vital life-signs back.