"Of a perianth, calyx, corolla, etc.: having or consisting of many separate members; not united. Opposed to monophyllous, gamophyllous. Compare polypetalous, polysepalous. Now chiefly historical", Late 18th cent.; earliest use found in Thomas Martyn (1735–1825), botanist. From poly- + -phyllous, probably after scientific Latin polyphyllus in plant names.