Definitions
1.NounA 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.
2.NounIn a nonparasitic way, using an animal's skin as a microhabitat.
3.NounIn a parasitic way, as an external parasite.