adeptus
/aˈdɛptəs/ /əˈdɛptəs/noun
Usually in plural, with the. A person who has attained knowledge of the secrets of alchemy, magic, and the occult, (now especially) an initiate into the secrets of a particular hermetic order or occult organization.
Origin
Mid 17th century; earliest use found in Thomas Vaughan (1621–1666), hermetic philosopher and alchemist. From post-classical Latin adeptus person who has attained knowledge of the secrets of alchemy, use as noun of classical Latin adeptus.