The Collaborative International Dictionary of English v.0.48:

Defilement \De*file"ment\, n. [Cf. F. d['e]filement. See
   Defile] (Mil.)
   The protection of the interior walls of a fortification from
   an enfilading fire, as by covering them, or by a high parapet
   on the exposed side.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Defilement \De*file"ment\, n. [From 3d Defile.]
   The act of defiling, or state of being defiled, whether
   physically or morally; pollution; foulness; dirtiness;
   uncleanness.
   [1913 Webster]

         Defilements of the flesh.                --Hopkins.
   [1913 Webster]

         The chaste can not rake into such filth without danger
         of defilement.                           --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

defilement
    n 1: the state of being polluted [syn: befoulment,
         defilement, pollution]