Sorry for who-posting in the year 2019 but the Doctor is actually so named because he wrote and successfully defended a dissertation at an accredited university whereas the Master completed a 2-year graduate program in his chosen field, which points to the existence of a third less-advanced and less-specialized counterpart, the Bachelor
The Bachelor is never seen in the show because he’s still living with his parents on Gallifrey, listlessly applying for jobs and stress-eating
I thought the bachelor was being fought over by 12 women in a big house
galaxy brain: The Bachelor Tv show has featured the same man for every season but he regenerates like the doctor