Source : Webster's Revised Unabridged Dictionary (1913)

Hermetically \Her*met"ic*al*ly\, adv.
   1. In an hermetical manner; chemically. --Boyle.

   2. By fusion, so as to form an air-tight closure.

   Note: A vessel or tube is hermetically sealed when it is
         closed completely against the passage of air or other
         fluid by fusing the extremity; -- sometimes less
         properly applied to any air-tight closure.

Source : WordNet®

hermetically
     adv : in an airtight manner; "this bag is hermetically sealed"