The Collaborative International Dictionary of English v.0.48:

Equine \E"quine\, a. [L. equinus, fr. equus horse; akin to Gr.
   ?, Skr. a?va, OS. ehu, AS. eh, eoh, Icel. j?r, OIr. ech, cf.
   Skr. a? to reach, overtake, perh. akin to E. acute, edge,
   eager, a. Cf. Hippopotamus.]
   Of, pertaining to, or resembling, a horse.
   [1913 Webster]

         The shoulders, body, things, and mane are equine; the
         head completely bovine.                  --Sir J.
                                                  Barrow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

equine
    adj 1: resembling a horse
    2: of or belonging to the family Equidae
    n 1: hoofed mammals having slender legs and a flat coat with a
         narrow mane along the back of the neck [syn: equine,
         equid]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "equine":
   Houyhnhnm, asinine, bovid, bovine, brood mare, caprid, caprine,
   charger, colt, courser, cowish, cowlike, critter, deerlike, dobbin,
   entire, entire horse, equestrian, filly, foal, gelding, goatish,
   goatlike, hircine, hoggish, hoofed, horse, horsy, mare, mount,
   mulish, nag, ovine, piggish, prancer, ruminant, sheepish,
   sheeplike, stallion, steed, stud, studhorse, swinish, tarpan,
   top horse, ungulate, war-horse, wild horse