The Collaborative International Dictionary of English v.0.48:

Incasement \In*case"ment\, n. [Cf. Casement.]
   [1913 Webster]
   1. The act or process of inclosing with a case, or the state
      of being incased.
      [1913 Webster]

   2. That which forms a case, covering, or inclosure.
      [1913 Webster]

WordNet (r) 3.0 (2006):

incasement
    n 1: the act of enclosing something in a case [syn:
         encasement, incasement]