D defs.my
Entry 3 senses Webster, 1913

Hermetic

· Her·met·ic · IPA /hə(ɹ)ˈmɛtɪk/
01 a. Of, pertaining to, or taught by, Hermes Trismegistus; as, hermetic philosophy. Hence: Alchemical; chemic.
  1. 1.
    Of, pertaining to, or taught by, Hermes Trismegistus; as, hermetic philosophy. Hence: Alchemical; chemic.
    “The alchemists, as the people were called who tried to make gold, considered themselves followers of Hermes, and often called themselves Hermetic philosophers.” — A. B. Buckley.
  2. 2.
    Of or pertaining to the system which explains the causes of diseases and the operations of medicine on the principles of the hermetic philosophy, and which made much use, as a remedy, of an alkali and an acid; as, hermetic medicine.
  3. 3.
    Made perfectly close or air-tight by fusion, so that no gas or spirit can enter or escape; as, an hermetic seal. See Note under Hermetically. See: Hermetically
Phrases & compounds
Hermetic art — alchemy.
Hermetic books — Books of the Egyptians, which treat of astrology.