A sorcerer is a practitioner of
sorcery i.e.
magic. The term is usually used to describe a
magician primarily concerned with
divination and communing with, or even controlling,
spirits.
The term "sorcerer" usually has a slightly negative connotation. Not necessarily a plainly evil being such as a warlock, there is usually the sense that a sorcerer is meddling with sinister forces more powerful than himself (e.g. Goethe's "Sorcerer's apprentice").
The word "sorcerer" has gender, the female version being sorceress.
Other terms for magic users are: