(Sanskrit अभ्यास) Practice, habit, drill, custom, study, use, military exercise, repeated or permanent exercise, multiplication, act of adding anything.
"Control of vrittis [modifications of mind] is done by abhyasa and vairagya. Of these, practice is the effort to secure steadiness of vrittis. Practice becomes firmly grounded when practiced for a long time, without any break, and with perfect devotion." — Patanjali, Yoga Sutras 1:12-14