Witch is a word that has been used in history to refer to various kind of sorceresses, with
various meanings, depending on the time
period and the cultural sphere it was used in. Today we usually use it to refer
to a generic evil female magician, like the female antagonists in many fairy
tales.
This way of seeing the witches come from
the Middle Ages when, because of the centrality of the Christian religion in
Europe, those who were considered capable of doing impossible things were
called witches (or wizards if they were men) and considered followers of the
Devil and, usually, sentenced to be burnt at the stake. Today we use the
expression witch trials to refer to
the enormous number of trials led against the ones who were supposed to practice witchcraft over the
course of time.