adj. (also hermetical)
1. with an airtight closure.
2 protected from outside agencies.
3 a of alchemy or other occult sciences (hermetic art). b esoteric.
Phrases and idioms:
hermetic seal an airtight seal (orig. as used by alchemists).
Derivatives:
hermetically adv. hermetism n.
Etymology: mod.L hermeticus irreg. f. Hermes Trismegistus thrice-greatest Hermes (as the founder of alchemy)