The Collaborative International Dictionary of English v.0.48:

Feline \Fe"line\, a. [L. felinus, fr. feles, felis, cat, prob.
   orig., the fruitful: cf. F. f['e]lin. See Fetus.]
   1. (Zool.) Catlike; of or pertaining to the genus Felis, or
      family Felid[ae]; as, the feline race; feline voracity.
      [1913 Webster]

   2. Characteristic of cats; sly; stealthy; treacherous; as, a
      feline nature; feline manners.
      [1913 Webster]

WordNet (r) 3.0 (2006):

feline
    adj 1: of or relating to cats; "feline fur"
    n 1: any of various lithe-bodied roundheaded fissiped mammals,
         many with retractile claws [syn: feline, felid]

Moby Thesaurus II by Grady Ward, 1.0:

134 Moby Thesaurus words for "feline":
   Cheshire cat, Chinchilla cat, Machiavellian, Machiavellic,
   Maltese cat, acute, alley cat, amphibian, aquatic, arch, artful,
   astute, back-door, backstairs, biped, blue cat, cagey, calico cat,
   canine, cannibal, canny, carnivore, cat, catlike, cattish, catty,
   clandestine, clever, cosmopolite, covert, crafty, cunning, cute,
   deceitful, deep, deep-laid, designing, diplomatic, felid, foxy,
   furtive, gib, gib-cat, gnawer, grimalkin, guileful, herbivore,
   hidlings, hole-and-corner, house cat, hugger-mugger, ingenious,
   insectivore, insidious, inventive, invertebrate, kit, kitling,
   kitten, kittenish, kitty, kitty-cat, knowing, leonine, lionlike,
   mammal, mammalian, marsupial, marsupialian, mouser, omnivore,
   pawky, politic, primate, privy, puss, pussy, pussycat, quadruped,
   quiet, ready, reptile, resourceful, rodent, ruminant, scavenger,
   scheming, serpentine, sharp, shifty, shrewd, silver cat, skulking,
   slick, slinking, slinky, slippery, sly, smooth, snaky, sneaking,
   sneaky, sophistical, stealthy, strategic, subtile, subtle, supple,
   surreptitious, tabby, tabby cat, tactical, tiger cat, tigerish,
   tom, tomcat, tortoise-shell cat, trickish, tricksy, tricky,
   under-the-counter, under-the-table, undercover, underground,
   underhand, underhanded, ungulate, unobtrusive, varmint, vermin,
   vertebrate, vulpine, wary, wily