Definition - What does Sadhaka mean?
Sadhaka is a Sanskrit term which describes someone who follows a certain sadhana, a spiritual practice or way of life, with the aim of achieving a certain goal. The term can be translated as meaning "spiritually adept."
Sometimes it is confused with a very similar term, abhyasi, which can be translated as "practitioner," but, while a practitioner repeats a mechanical practice, a sadhaka must go further and practice with deep inner focus, intelligence and perception.
Yogapedia explains Sadhaka
Sadhaka is derived from the root word, sadh, meaning "to accomplish." Once the sadhaka reaches their goal, they transform into a siddha, or "one who is accomplished." In yoga, a sadhaka is a yogi devoted to the practice of yoga, seeking liberation deep inside the soul.
According to B.K.S. Iyengar, one of the most famous yoga teachers of all time, a sadhaka uses yoga to gain knowledge, light and liberation. It also helps to purify the body and soul.