Extremely rigid in self-denial and devotions; austere; severe.

In the early church, one who devoted himself to a solitary and contemplative life, characterized by devotion, extreme self-denial, and self-mortification; a hermit; a recluse; hence, one who practices extreme rigor and self-denial in religious things.

the practice of self-denial as a way of religious life; from the Greek asketikos, meaning laborious

practices self denial as spiritual discipline