1. [adj]  practicing great self-denial; "Be systematically ascetic...do...something for no other reason than that you would rather not do it"- William James; "a desert nomad's austere life"; "a spartan diet"; "a spartan existence"
2. [adj]  pertaining to or characteristic of an ascetic; "ascetic practices"

ASCETICAL is a 9 letter word that starts with A.