Siddha
The term siddha is derived from the root sidh which may be translated as "achievement" or "fullfilment." In the Vedic period, the Siddhas were a type of semi-divine, sky-dwelling celestial beings. Later, the term became associated with adept human practitioners - those who have "achieved". Two Tantric lineages which were particularly identified with the term were the Nath Siddhas and the Tamil Siddhas.