[her.met.ic] also her.met.i.cal adj [NL hermeticus, fr. Hermet-, Hermes Trismegistus] (1605) 1 often cap a: of or relating to the Gnostic 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
2. [fr. the belief that Hermes Trismegistus invented a magic seal to keep vessels airtight] a: airtight "~ seal" b: impervious to external influence "trapped inside the ~ military machine --Jack Newfield" c: recluse, solitary "leads a ~ life" -- her.met.i.cal.ly adv