hermetically

from WordNet (r) 3.0 (2006)

hermetically
    adv 1: in an airtight manner; "this bag is hermetically sealed"

from The Collaborative International Dictionary of English v.0.48

Hermetically \Her*met"ic*al*ly\, adv.
   1. In an hermetical manner; chemically. --Boyle.
      [1913 Webster]

   2. By fusion, so as to form an air-tight closure.
      [1913 Webster]

   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.
         [1913 Webster]