The Collaborative International Dictionary of English v.0.48:

Horny \Horn"y\, a. [Compar. Hornier; superl. Horniest.]
   1. Having horns or hornlike projections. --Gay.
      [1913 Webster]

   2. Composed or made of horn, or of a substance resembling
      horn; of the nature of horn. "The horny . . . coat of the
      eye." --Ray.
      [1913 Webster]

   3. Hard; callous. "His horny fist." --Dryden.
      [1913 Webster]

WordNet (r) 3.0 (2006):

horny
    adj 1: feeling great sexual desire; "feeling horny" [syn:
           aroused, horny, randy, ruttish, steamy, turned
           on(p)]
    2: having horns or hornlike projections; "horny coral"; "horny
       (or horned) frog"
    3: made of horn (or of a substance resembling horn) [syn:
       corneous, hornlike, horny]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "horny":
   acanthoid, acanthous, acicular, acuate, aculeate, aculeiform,
   acuminate, acute, animal, aphrodisiomaniacal, barbed, bawdy, bony,
   carnal, cement, cemental, clitoromaniacal, concrete, concupiscent,
   corneous, cornuted, cusped, cuspidate, dense, diamondlike, dirty,
   dure, ejaculatory, erotic, eroticomaniacal, erotomaniacal, fleshly,
   flintlike, flinty, goatish, granitelike, granitic, gynecomaniacal,
   hard, hard as nails, hardhearted, hispid, horned, hot, hot-blooded,
   hysteromaniacal, iron-hard, ironlike, itching, ithyphallic,
   lapideous, lascivious, lecherous, lewd, libidinous, lickerish,
   lithoid, lithoidal, lubricious, lustful, marble, marblelike,
   mucronate, needle-pointed, needle-sharp, nymphomaniacal, obdurate,
   obscene, orgasmic, orgastic, osseous, passionate, pointed, priapic,
   pronged, prurient, randy, resistant, resistive, rocklike, rocky,
   salacious, satyric, sensual, sex-starved, sexual, sexy,
   sharp-pointed, solid, spiculate, spiked, spiky, spined, spinous,
   spiny, steamy, steellike, steely, stonelike, stony, tapered,
   tapering, tined, toothed, tough, unbated, unsatisfied