adept, n. — Green’s Dictionary of Slang

adept n.

[Lat. adeptus, skilled in; a Med. alchemist who had attained ‘the great secret’ was entitled adeptus, completely skilled (in all the secrets of his art)]

1. a conjuror.

1721		R. Neve in Daniel Merry England in the Olden Time I 277: An adept must be of an audacious spirit with a nimble conveyance and a vocabulary of cabalistic phrases to astonish the beholder.
1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.

2. an alchemist.

1889–90

Barrère & Leland Dict. of Sl., Jargon and Cant I 16/2: (Old cant), an alchemist.