Epizoon

Noun

1. A microorganism (such as a yeast-type fungus or a protozoon) that grows on the surface of an animal host, as: In a nonparasitic way, using an animal's skin as a microhabitat. In a parasitic way, as an external parasite.<!--This sense appears to be outdated.-->
2. In a nonparasitic way, using an animal's skin as a microhabitat.
3. In a parasitic way, as an external parasite.<!--This sense appears to be outdated.-->