formicary

from WordNet (r) 3.0 (2006)

formicary
    n 1: a mound of earth made by ants as they dig their nest [syn:
         {anthill}, {formicary}]

from The Collaborative International Dictionary of English v.0.48

Formicary \For"mi*ca*ry\, n. [LL. formicarium, fr. L. formica an
   ant.] (Zool.)
   The nest or dwelling of a swarm of ants; an ant-hill.
   [1913 Webster]