Incarnation

An incarnation was the term applied to the bodies/selves/lives of a Time Lord. While it was sometimes used interchangeably with "regeneration," (TV: The Keeper of Traken) incarnations were actually the result of this process, with Time Lords regenerating from one incarnation to another. Barring special circumstances, a Time Lord could only have thirteen incarnations, (TV: The Deadly Assassin) before their symbiotic nuclei started to break down. (AUDIO: Trial of the Valeyard)

The Eleventh Doctor thought he had never used the word incarnation in that capacity, but was proven wrong by Ally. (COMIC: The Girl Who Loved Doctor Who)