Where does “pleomorphy” come from?

pleomorphy (English) comes from English pleo-, from Ancient Greek πλείων, from Proto-Hellenic *pleíhōn, from Proto-Indo-European *pléh₁yōs — full.

Ancestry of “pleomorphy”, step by step

StepLanguageWordMeaning
1Englishpleo-supernumerary; many
2Ancient Greekπλείωνmore, comparative degree of πολύς; more; more,...
3Proto-Hellenic*pleíhōn—
4Proto-Indo-European*pléh₁yōsfull
Every word from Proto-Indo-European *pléh₁yōs →Every word from Proto-Hellenic *pleíhōn →Every word from Ancient Greek πλείων →