adept

1655–65; < Medieval Latin adeptus one who has attained (the secret of transmuting metals), noun use of L past participle of adipiscī to attain to (ad- ad- + -ep-, combining form of ap- in aptus apt + -tus past participle suffix)

The Latin noun adepti “those who have attained knowledge of the esoteric secrets of alchemy,” seems first to have appeared in the works of the Swiss physician and alchemist Paracelsus, and later, in the works of the Flemish chemist and physician Jan Baptista van Helmont. Twice in Ulysses, James Joyce uses the noun adept in reference to Madame Blavatsky and her Theosophical Society.
The noun adept originally meant “one who has gained knowledge of the of alchemy, the occult, hermetic philosophy, and magic,” which is Joyce’s use of the word. As both noun and adjective, it developed the more general sense “(a person) highly skilled or proficient in a subject.” The adjective adept appears about a quarter of a century before the noun, but they have the same etymology, coming from Latin adeptus, the perfect participle of adipiscī “to overtake, catch up with, obtain, achieve.”
Adipiscī is a compound formation of the preposition and prefix ad, ad-, here in the sense of “reaching,” and the verb apiscī “to seize hold of, grasp.” Apiscī is a frequentative verb formed from the rare verb apere “to fasten, attach, bind,” whose perfect participle aptus “tied, bound, connected, fitted with, ready for” is very common in Latin and is the source of English apt.