The Collaborative International Dictionary of English v.0.48:

Dialyzer \Di"a*ly`zer\, n.
   The instrument or medium used to effect chemical dialysis.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dialyzer
    n 1: a medical instrument for separating substances in solution
         by unequal diffusion through semipermeable membranes [syn:
         dialyzer, dialysis machine]