The Collaborative International Dictionary of English v.0.48:

Pill \Pill\, n. [F. pilute, L. pilula a pill, little ball, dim.
   of L. pila a ball. Cf. Piles.]
   1. A medicine in the form of a little ball, or small round
      mass, to be swallowed whole.
      [1913 Webster]

   2. Figuratively, something offensive or nauseous which must
      be accepted or endured. --Udall.
      [1913 Webster]

   Pill beetle (Zool.), any small beetle of the genus
      Byrrhus, having a rounded body, with the head concealed
      beneath the thorax.

   Pill bug (Zool.), any terrestrial isopod of the genus
      Armadillo, having the habit of rolling itself into a
      ball when disturbed. Called also pill wood louse.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pill bug
    n 1: small terrestrial isopod with a convex segmented body that
         can roll up into a ball