'oomycete' originates from Modern New Latin (taxonomic usage), ultimately built from Greek elements: 'ōon' meaning 'egg' and 'mykēs' meaning 'fungus'.

'oomycete' was formed from the New Latin taxonomic name 'Oomycetes' (class/group name). Historically, organisms now placed in Oomycota were once grouped with 'phycomycetes' or broadly treated as fungi, but were reclassified as a separate lineage as microscopic and molecular studies developed.

Initially used broadly for 'egg fungi' or fungus-like organisms, the term has become more precise, denoting members of the distinct lineage Oomycota (not true fungi) that share specific morphological and genetic traits.