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
hermetically sealed very tightly closed so that air cannot get in or out = airtight (hermeticus, from Hermes Trismegistus, a magician in ancient stories who invented a way of keeping air out of containers)