The Collaborative International Dictionary of English v.0.48:

macabre \macabre\ (m[.a]*k[aum]"b[~e]r) adj.
   1. portraying human injury or death in a way so as to
      inspiring shock or horror; gruesome; ghastly; as, macabre
      tortures conceived by madmen. [Also spelled macaber.]

   Syn: ghastly, grisly, gruesome, lurid.
        [WordNet 1.5]

   2. Pertaining to or portraying the grim aspects of death, or
      the allegorical dance of death.
      [PJC]