of, pertaining to, or taught by, hermes trismegistus; as, hermetic philosophy. hence: alchemical; chemic.-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.-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.