Source : Webster's Revised Unabridged Dictionary (1913)

Tardigrada \Tar`di*gra"da\, n. pl. [NL. See {Tardigrade}, a.]
   1. (Zo["o]l.) A tribe of edentates comprising the sloths.
      They are noted for the slowness of their movements when on
      the ground. See {Sloth}, 3.

   2. (Zo["o]l.) An order of minute aquatic arachnids; -- called
      also {bear animalcules}, {sloth animalcules}, and {water
      bears}.

Source : WordNet®

Tardigrada
     n : in some classifications considered a separate phylum:
         microscopic arachnid-like invertebrates living in water
         or damp moss having 4 pairs of legs and instead of a
         mouth a pair of stylets or needle-like piercing organs
         connected with the pharynx [syn: {class Tardigrada}]