Actually, if you want to get into "true definitions" you'll need to pay attention to etymology, anthology, and how the word was originally used.
Witchcraft versus sorcery in anthology in particular. Witchcraft is a natural, inborn ability to use an invisible, internal force to cause change in the world without the need of spells, rituals, etc. Sorcery involves a learned ability to use an invisible force to cause change in the world through the use of spells, rituals, etc.
Therefore, most folks aren't witches, they are sorcerers. Especially if they require study, rituals, spells, etc, in order to practice.