Definition of protophyte in US English:

protophyte

noun

Botany
historical
  • An organism belonging to the class Protophyta; especially a unicellular alga.

Origin

Mid 19th century; earliest use found in The Southern Quarterly Review. From proto- + -phyte, after scientific Latin protophytum.

Pronunciation

protophyte

/ˈprəʊtəfʌɪt/