{ } a. [ F. hermétique. See Note under Hermes, 1. ] 1. Of, pertaining to, or taught by, Hermes Trismegistus; as, hermetic philosophy. Hence: Alchemical; chemic. “Delusions of the hermetic art.” Burke. [ 1913 Webster ]

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. [ 1913 Webster ]

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. [ 1913 Webster ]

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. [ 1913 Webster ]

Hermetic art, alchemy. --
Hermetic books. (a) Books of the Egyptians, which treat of astrology. (b) Books which treat of universal principles, of the nature and orders of celestial beings, of medicine, and other topics. [ 1913 Webster ]

adv. 1. In an hermetical manner; chemically. Boyle. [ 1913 Webster ]

2. By fusion, so as to form an air-tight closure. [ 1913 Webster ]

☞ A vessel or tube is hermetically sealed when it is closed completely against the passage of air or other fluid by fusing the extremity; -- sometimes less properly applied to any air-tight closure. [ 1913 Webster ]