abstainer

noun

1. One who abstains; especially, one who abstains from something, such as the use of alcohol or drugs, or one who abstains for religious reasons; one who practices self-denial.

   “To one of my very nervous patients, who was an abstainer, whose fancy was fixed on his mother, and who repeatedly dreamed of climbing stairs accompanied by his mother, I once remarked that moderate masturbation would be less harmful to him than enforced abstinence.”

   “He was a total abstainer and a nonsmoker, had no recreations except a daily hour in the gymnasium, and had taken a vow of celibacy, believing marriage and the care of a family to be incompatible with a twenty-four-hour-a-day devotion to duty.”

   “'Never himself touches a drop of the stuff, you understand. Having been an abstainer since the age of seven or something. A clerky figure even as a child.'”