The Collaborative International Dictionary of English v.0.48:

Casern \Ca"sern\, n. [F. caserne.]
   A lodging for soldiers in garrison towns, usually near the
   rampart; barracks. --Bescherelle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

casern
    n 1: military barracks in a garrison town