The Collaborative International Dictionary of English v.0.48:

Horned \Horned\, a.
   Furnished with a horn or horns; furnished with a hornlike
   process or appendage; as, horned cattle; having some part
   shaped like a horn.
   [1913 Webster]

         The horned moon with one bright star
         Within the nether tip.                   --Coleridge.
   [1913 Webster]

   Horned bee (Zool.), a British wild bee (Osmia bicornis),
      having two little horns on the head.

   Horned dace (Zool.), an American cyprinoid fish (Semotilus
      corporialis) common in brooks and ponds; the common chub.
      See Illust. of Chub.

   Horned frog (Zool.), a very large Brazilian frog
      (Ceratophrys cornuta), having a pair of triangular horns
      arising from the eyelids.

   Horned grebe (Zool.), a species of grebe (Colymbus
      auritus), of Arctic Europe and America, having two dense
      tufts of feathers on the head.

   Horned horse (Zool.), the gnu.

   Horned lark (Zool.), the shore lark.

   Horned lizard (Zool.), the horned toad.

   Horned owl (Zool.), a large North American owl (Bubo
      Virginianus), having a pair of elongated tufts of
      feathers on the head. Several distinct varieties are
      known; as, the Arctic, Western, dusky, and striped horned
      owls, differing in color, and inhabiting different
      regions; -- called also great horned owl, horn owl,
      eagle owl, and cat owl. Sometimes also applied to the
      long-eared owl. See Eared owl, under Eared.

   Horned poppy. (Bot.) See Horn poppy, under Horn.

   Horned pout (Zool.), an American fresh-water siluroid fish;
      the bullpout.

   Horned rattler (Zool.), a species of rattlesnake (Crotalus
      cerastes), inhabiting the dry, sandy plains, from
      California to Mexico. It has a pair of triangular horns
      between the eyes; -- called also sidewinder.

   Horned ray (Zool.), the sea devil.

   Horned screamer (Zool.), the kamichi.

   Horned snake (Zool.), the cerastes.

   Horned toad (Zool.), any lizard of the genus Phrynosoma,
      of which nine or ten species are known. These lizards have
      several hornlike spines on the head, and a broad, flat
      body, covered with spiny scales. They inhabit the dry,
      sandy plains from California to Mexico and Texas. Called
      also horned lizard.

   Horned viper. (Zool.) See Cerastes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

horned
    adj 1: having a horn or horns or hornlike parts or horns of a
           particular kind; "horned viper"; "great horned owl"; "the
           unicorn--a mythical horned beast"; "long-horned cattle"
           [ant: hornless]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "horned":
   Cynthian, S-shaped, acanthoid, acanthous, acicular, acuate,
   aculeate, aculeiform, acuminate, acute, barbed, bicorn, corniform,
   cornuted, crescent, crescent-shaped, crescentic, crescentiform,
   crescentlike, cusped, cuspidate, falcate, falciform, hispid,
   horn-shaped, horny, lunar, lunate, luniform, lunular, menisciform,
   meniscoid, moon-shaped, moonlike, mucronate, needle-pointed,
   needle-sharp, pointed, pronged, semicircular, semilunar,
   sharp-pointed, sickle-like, sickle-shaped, sigmoid, spiculate,
   spiked, spiky, spined, spinous, spiny, tapered, tapering, tined,
   toothed, two-horned, unbated