Magick is an Early Modern English spelling for magic. Magick, in the context of Aleister Crowley's Thelema, is a term used to differentiate the occult from stage magic and is defined as "the Science and Art of causing Change to occur in conformity with Will", including both "mundane" acts of will as well as ritual magic.
Usage
See Special:Whatlinkshere/Etymology:Magick for a list of articles using this term.
This is an etymology page: a page detailing the origins of terminology used in the series in regards to real world culture and history.