World of Darkness
The term does explicitly not refer to mortals, including those with numina: un-Awakened sorcerers, psychics and mediums, mortals with True Faith, and mortals who have been touched by the supernatural, such as ghouls, Kinfolk, consorts, the Enchanted, Kinain, or thralls. It is unclear if the imbued qualify as supernaturals or not, although the imbued are effectively treated as mortals by their own edges.
Chronicles of Darkness
Though never explicitly defined in the source material, the term "supernatural" is commonly used as a general descriptor for anything that goes beyond the limits of ordinary human understanding, and is contrasted with the mortal or mundane. If a being is not mortal, then it is supernatural.
Due to the mechanical requirement that a character be mortal to acquire various Merits described as supernatural, it is a grey area as to whether supernaturally-touched mortals (e.g. Atariya, psychics, mediums, etc.) should be considered supernatural themselves.