This word has changed a bit since Webster's days.
These days apoplectic is more likely to mean extremely angry, to the point of loosing control of ones temper. 'Apoplectic' usually stops short of violence, but not much short. This may come from the use of the word apoplexy to mean 'an effusion of blood', thus, it would refer to someone white-faced with anger. (Ironically, some dictionaries will use 'red-faced with anger' as a synonym).