Where does “monophyletic” come from?

Monophyletic derives from Ancient Greek μόνος (mónos, "single") and φῦλον (phûlon, "tribe" or "race"), both ultimately traceable to Proto-Indo-European roots meaning "to grow" and "to scratch or rub."

monophyletic (English): Of, pertaining to, or affecting a single phylum (or other taxon) of organisms