The Collaborative International Dictionary of English v.0.48:

Wringer \Wring"er\, n.
   1. One who, or that which, wrings; hence, an extortioner.
      [1913 Webster]

   2. A machine for pressing water out of anything, particularly
      from clothes after they have been washed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

wringer
    n 1: a clothes dryer consisting of two rollers between which the
         wet clothes are squeezed