The Collaborative International Dictionary of English v.0.48:

Trivet \Triv"et\, n. [Probably through French fr. L. tripes,
   -edis, three-footed; tri- (see Tri-)+ pes, pedis, foot: cf.
   F. tr['e]pied. See Foot, and cf. Tripod.]
   1. A tree-legged stool, table, or other support; especially,
      a stand to hold a kettle or similar vessel near the fire;
      a tripod. [Written also trevet.]
      [1913 Webster]

   2. A weaver's knife. See Trevat. --Knight.
      [1913 Webster]

   Trivet table, a table supported by three legs. --Dryden.
      [1913 Webster]

WordNet (r) 3.0 (2006):

trivet
    n 1: a three-legged metal stand for supporting a cooking vessel
         in a hearth
    2: a stand with short feet used under a hot dish on a table

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "trivet":
   andiron, chain, clover, coal tongs, crane, crook, damper,
   deuce-ace, fire hook, fire tongs, firedog, grate, grating, grid,
   griddle, gridiron, grill, griller, leash, lifter, poker, pothook,
   salamander, set of three, shamrock, spit, tercet, ternary, ternion,
   terzetto, three, threesome, tierce, tongs, trefoil, trey, triad,
   trialogue, triangle, tricorn, trident, triennium, trihedron,
   trilogy, trimester, trine, trinity, trinomial, trio, triphthong,
   triple crown, triple threat, triplet, triplopy, tripod, triptych,
   trireme, triseme, triskelion, trisul, triumvirate, triunity,
   troika, turnspit