The Collaborative International Dictionary of English v.0.48:

Slimy \Slim"y\, a. [Compar. Slimier; superl. Slimiest.]
   Of or pertaining to slime; resembling slime; of the nature of
   slime; viscous; glutinous; also, covered or daubed with
   slime; yielding, or abounding in, slime.
   [1913 Webster]

         Slimy things did crawl with legs
         Upon the slimy sea.                      --Coleridge.
   [1913 Webster]

WordNet (r) 3.0 (2006):

slimy
    adj 1: covered with or resembling slime; "a slimy substance
           covered the rocks" [syn: slimed, slimy]
    2: morally reprehensible; "would do something as despicable as
       murder"; "ugly crimes"; "the vile development of slavery
       appalled them"; "a slimy little liar" [syn: despicable,
       ugly, vile, slimy, unworthy, worthless, wretched]

Moby Thesaurus II by Grady Ward, 1.0:

132 Moby Thesaurus words for "slimy":
   abject, adhesive, adulatory, amylaceous, barfy, bland, blandishing,
   blarneying, buttery, cajoling, clabbered, clammy, clotted,
   coagulated, complimentary, courtierly, courtly, crappy, creeping,
   curdled, disgusting, doughy, fair-spoken, fawning, fecal, feculent,
   fetid, filthy, fine-spoken, flattering, flyblown, foul, fulsome,
   gaumy, gelatinous, glairy, gloppy, gluelike, gluey, glutenous,
   glutinose, glutinous, gooey, grumous, gumbo, gumbolike, gumlike,
   gummous, gummy, gunky, gushing, heavy, honey-mouthed,
   honey-tongued, honeyed, icky, insincere, insinuating, inspissated,
   jelled, jellied, jellylike, maggoty, malodorous, mealymouthed,
   mephitic, mucilaginous, mucky, mucous, mushy, nasty, nauseating,
   obsequious, odious, oily, oily-tongued, oozy, ordurous, pasty,
   puky, putrid, rank, repulsive, ropy, rotten, scabby, scummy,
   scurfy, servile, shitty, slabby, slippery, slithery, slobbery,
   sloppy, sloshy, sludgy, slushy, smarmy, smooth, smooth-spoken,
   smooth-tongued, soapy, soft-soaping, sposhy, squashy, squishy,
   squushy, starchy, sticky, stodgy, stringy, sycophantic, syrupy,
   tacky, tenacious, thick, thickened, toadying, tough, tremelloid,
   tremellose, uliginous, unctuous, vile, viscid, viscose, viscous,
   vomity, wheedling, wormy, yecchy