DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   casing
       n 1: the housing or outer covering of something; "the clock has
            a walnut case" [syn: shell, case, casing]
       2: the outermost covering of a pneumatic tire
       3: the enclosing frame around a door or window opening; "the
          casings had rotted away and had to be replaced" [syn:
          casing, case]