The Collaborative International Dictionary of English v.0.48:

Toad \Toad\, n. [OE. tode, tade, AS. t[=a]die, t[=a]dige; of
   unknown origin. Cf. Tadpole.] (Zool.)
   Any one of numerous species of batrachians belonging to the
   genus Bufo and allied genera, especially those of the
   family Bufonidae. Toads are generally terrestrial in their
   habits except during the breeding season, when they seek the
   water. Most of the species burrow beneath the earth in the
   daytime and come forth to feed on insects at night. Most
   toads have a rough, warty skin in which are glands that
   secrete an acrid fluid.
   [1913 Webster]

   Note: The common toad (Bufo vulgaris) and the natterjack
         are familiar European species. The common American toad
         (Bufo lentiginosus) is similar to the European toad,
         but is less warty and is more active, moving chiefly by
         leaping.
         [1913 Webster]

   Obstetrical toad. (Zool.) See under Obstetrical.

   Surinam toad. (Zool.) See Pita.

   Toad lizard (Zool.), a horned toad.

   Toad pipe (Bot.), a hollow-stemmed plant (Equisetum
      limosum) growing in muddy places. --Dr. Prior.

   Toad rush (Bot.), a low-growing kind of rush (Juncus
      bufonius).

   Toad snatcher (Zool.), the reed bunting. [Prov. Eng.]

   Toad spittle. (Zool.) See Cuckoo spit, under Cuckoo.

   Tree toad. (Zool.) See under Tree.
      [1913 Webster]

WordNet (r) 3.0 (2006):

toad
    n 1: any of various tailless stout-bodied amphibians with long
         hind limbs for leaping; semiaquatic and terrestrial species
         [syn: frog, toad, toad frog, anuran, batrachian,
         salientian]

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "toad":
   amphibian, apple-polisher, ass-licker, backscratcher, backslapper,
   batrachian, bootlick, bootlicker, brown-nose, brownie, bullfrog,
   clawback, courtier, creature, cringer, croaker, dog, dupe, fawner,
   flatterer, flunky, footlicker, frog, groveler, handshaker, helot,
   hoppytoad, hoptoad, instrument, jackal, kowtower, lackey,
   led captain, lickspit, lickspittle, mealymouth, minion, newt,
   paddock, peon, polliwog, prick, puppet, salamander, scum, serf,
   shit, shithead, skunk, slave, snake, spaniel, stinker, stooge,
   suck, sycophant, tadpole, timeserver, toadeater, toady, tool,
   tree frog, tree toad, truckler, tufthunter, turd, yes-man



The Jargon File (version 4.4.7, 29 Dec 2003):

toad
 vt.

    1. Notionally, to change a MUD player into a toad.

    2. To permanently and totally exile a player from the MUD. A very serious
    action, which can only be done by a MUD wizard; often involves a lot of
    debate among the other characters first. See also frog, FOD.