hermetic

the word 'hermetic' derives from the latin 'hermeticus', which in turn originates from the greek 'hermētikos', meaning "of hermes". this association refers to hermes trismegistus, the legendary hellenistic figure who syncretized the greek god hermes with the egyptian god thoth, and to whom a body of mystical, alchemical, and philosophical writings (the hermetica) was attributed. the sense of "completely sealed" arose from the belief that hermes trismegistus discovered the secret of an airtight seal, a concept crucial in alchemical processes to prevent the escape of vapors. thus, the modern meaning evolved from the literal, practical seal of alchemy to any perfectly airtight closure, while also retaining its abstract connection to occult and esoteric knowledge.

this word is a loanword from latin and greek, adopted as a simplex unit into english. it does not contain separable morphemes within its modern english spelling.