The Collaborative International Dictionary of English v.0.48:

maltreat \mal*treat"\ (m[a^]l*tr[=e]t"), v. t. [imp. & p. p.
   Maltreated; p. pr. & vb. n. Maltreating.] [Mal- + treat:
   cf. F. maltraiter.]
   To treat ill; to abuse; to treat roughly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

maltreated
    adj 1: subjected to cruel treatment; "an abused wife" [syn:
           abused, ill-treated, maltreated, mistreated]
           [ant: unabused]