The Collaborative International Dictionary of English v.0.48:

Polyhedral \Pol`y*he"dral\, Polyhedrical \Pol`y*hed"ric*al\, a.
   [See Polyhedron.] (Geom.)
   Having many sides, as a solid body.
   [1913 Webster]

   Polyhedral angle, an angle bounded by three or more plane
      angles having a common vertex.
      [1913 Webster]

WordNet (r) 3.0 (2006):

polyhedral
    adj 1: of or relating to or resembling a polyhedron

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "polyhedral":
   bifacial, bilateral, dihedral, flanked, handed, lateral,
   many-sided, multiangular, multilateral, one-sided, polygonal,
   prismatic, prismoid, pyramidal, pyramidic, quadrilateral, sided,
   tetrahedral, three-sided, trihedral, trilateral, triquetrous,
   two-sided, unilateral