ar·chi·my·ce·tes \ˌärkəˌmīˈsēd.ēz\noun plural Usage: capitalized Etymology: New Latin, from archi- + -mycetes 1.in some classifications: a subclass or order of Phycomycetes coextensive with Chytridiales 2.in some classifications: a class of primitive fungi comprising the Chytridiales and certain related forms