Epizoic

from WordNet (r) 3.0 (2006)

epizoic
    adj 1: living or growing on the exterior surface of an animal
           usually as a parasite; "an epizoic plant parasite" [ant:
           {endozoic}, {entozoan}, {entozoic}]

from The Collaborative International Dictionary of English v.0.48

Epizoic \Ep`i*zo"ic\, a. (Zo["o]l.)
   Living upon the exterior of another animal; ectozoic; -- said
   of external parasites.
   [1913 Webster]

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