The Collaborative International Dictionary of English v.0.48:

Pismire \Pis"mire\, n. [Piss + mire; so called because it
   discharges a moisture vulgarly considered urine. See Mire
   an ant.] (Zool.)
   An ant, or emmet.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pismire
    n 1: social insect living in organized colonies;
         characteristically the males and fertile queen have wings
         during breeding season; wingless sterile females are the
         workers [syn: ant, emmet, pismire]