epizoon

noun, plural ep·i·zo·a [ep-uh–zoh–uh] /ˌɛp əˈzoʊ ə/. Biology.

1. an external parasite or commensal on the body of an animal; ectozoon.

noun plural -zoa (-ˈzəʊə)

1. an animal, such as a parasite, that lives on the body of another animal

n. pl. ep•i•zo•a (-zō′ə)

1. An epizoic organism.