\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}.