adjective her·met·ic \(ˌ)hər-ˈme-tik\

: closed tightly so that no air can go in or out

Full Definition of HERMETIC

often capitalized
a :  of or relating to the mystical and alchemical writings or teachings arising in the first three centuries a.d. and attributed to Hermes Trismegistus
b :  relating to or characterized by occultism or abstruseness :  recondite
[from the belief that Hermes Trismegistus invented a magic seal to keep vessels airtight]
a :  airtight <hermetic seal>
b :  impervious to external influence <trapped inside the hermetic military machine — Jack Newfield>
c :  recluse, solitary <leads a hermetic life>
her·met·i·cal·ly \-ti-k(ə-)lē\ adverb

Variants of HERMETIC

her·met·ic also her·met·i·cal \-ti-kəl\

Origin of HERMETIC

Medieval Latin hermeticus, from Hermet-, Hermes Trismegistus
First Known Use: 1605

Other Religion (Eastern and Other) Terms

Zen, antinomian, avatar, gnosticism, illuminati, ineffable, karma, koan, mantra
Medical Dictionary


adjective her·met·ic \(ˌ)hər-ˈmet-ik\

Medical Definition of HERMETIC

:  being airtight or impervious to air
her·met·i·cal·ly \-i-k(ə-)lē\ adverb

Biographical Note for HERMETIC

Her·mes Tris·me·gis·tus, \ˈhər-(ˌ)mēz-ˌtris-mə-ˈjis-təs\ Greek mythological character. Hermes Trismegistus was identified by the Greeks with the Egyptian god Thoth. To him was ascribed authorship of various works on astrology, magic, alchemy, and medicine. It was also believed that he had invented a magic seal to keep vessels airtight, and from his name the adjective hermetic meaning airtight was derived.


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