According to many theological dictionaries Apostasy is "the total repudiation of the Christian faith." While this term may fit a number of individuals who have left the JW religion, most notably Lloyd Evans, Apostasy should not be applied to all ex-JWs.
For example those ex-JWs who join another Christian Church have not repudiated the Christian faith. Instead they have merely rejected some of the Watchtower's questionable doctrines and beliefs. Thus they are not apostates. According to the dictionary they are "Heretics." Of course the JW GB refuses to use that term in describing ex-JWs for obvious reasons.
However, there is another group of ex-JWs, and this may also include some still associating. These are the schismatics. Schism in this case is the refusal of submission to the JW GB, while accepting most Watchtower beliefs. In fact there used to be a small group of schismatic JWs here in Northern California. They called themselves "Jehovah's Witnesses Independent of the Watchtower." These folks believed all the JW doctrines. However, they rejected the GB.
Since I joined the Anglican Church after leaving the JWs, I'm a Heretic, not an apostate.