"Hermetical" is a word in ENGLISH

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.