epizoan

from WordNet (r) 3.0 (2006)

epizoan
    adj 1: of or relating to epizoa [syn: {epizoan}, {ectozoan}]
    n 1: any external parasitic organism (as fleas) [syn:
         {ectoparasite}, {ectozoan}, {ectozoon}, {epizoan},
         {epizoon}]

from The Collaborative International Dictionary of English v.0.48

Epizoan \Ep`i*zo"an\, n. (Zo["o]l.)
   An epizo["o]n.
   [1913 Webster]