The commonly accepted etymology derives warlock from the Old English wǣrloga meaning "oathbreaker" or "deceiver." A derivation from the Old Norse varð-lokkur, "caller of spirits," has also been suggested; however, the Oxford English Dictionary considers this etymology inadmissible.
The Oxford English Dictionary also provides the following meanings of the word: Warlock v1 Obs. (ex. dial.) rare, also warloke: To secure (a horse) as with a fetterlock. Warlock v2: To bar against hostile invasion.
Warlocks appear in a number of fantasy and science fiction novels, movies and games. They may be portrayed as humans who have attained magical or mystical powers, often evil, such as in the fantasy television series Charmed, in which warlocks are the evil counterparts to good witches and can be either male or female. Elsewhere, the distinction between "warlock" and "witch" may be purely one of sex, such as in the television series Bewitched, Dark Shadows and Buffy the Vampire Slayer. Alternatively, warlocks may be portrayed as a separate species or alien race, such as in the comic book series Nemesis the Warlock. Occasionally the term is used to refer to technological wizardry rather than magic, such as in Christopher Stasheff's Warlock of Gramarye series of novels. In the popular online game World of Warcraft, a Warlock is a playable class that uses Shadow (Dark) and fire magic offensively along with summoning demons as minions and draining life from enemies; in World of Warcraft, warlock is not gender specific, meaning players can play as male and female warlocks. The 3.5th edition of popular role playing game Dungeons and Dragons introduced a Warlock character class as well in the Complete Arcane, which gains its magic through a pact with a powerful and otherworldly being such as a devil, demon, or faerie, instead of the game's more traditional methods of faith, study, or innate power.