The Collaborative International Dictionary of English v.0.48:

Clammy \Clam"my\, a. [Compar. Clammier; superl. Clammiest.]
   [Cf. AS. cl[=a]m clay. See Clam to clog, and cf. Clay.]
   Having the quality of being viscous or adhesive; soft and
   sticky; glutinous; damp and adhesive, as if covered with a
   cold perspiration.
   [1913 Webster]

WordNet (r) 3.0 (2006):

clammy
    adj 1: unpleasantly cool and humid; "a clammy handshake";
           "clammy weather"; "a dank cellar"; "dank rain forests"
           [syn: clammy, dank]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "clammy":
   adhesive, amylaceous, bathed in sweat, beaded with sweat,
   clabbered, close, clotted, coagulated, curdled, damp, diaphoretic,
   doughy, drenched with sweat, foggy, gaumy, gelatinous, glairy,
   gluelike, gluey, glutenous, glutinose, glutinous, gooey, grumous,
   gumbo, gumbolike, gumlike, gummous, gummy, heavy, humid,
   in a sweat, inspissated, jelled, jellied, jellylike, misty, moist,
   mucilaginous, muggy, pasty, perspiring, perspiry, ropy, slabby,
   slimy, slithery, starchy, sticky, stodgy, stringy, sudatory,
   sudoric, sudorific, sweating, sweaty, syrupy, tacky, tenacious,
   thick, thickened, tough, tremelloid, tremellose, viscid, viscose,
   viscous, wet, wet with sweat, wilted