Where does “πληθύω” come from?

πληθύω (Ancient Greek) comes from Ancient Greek πληθύς, from Ancient Greek πίμπλημι, from Proto-Indo-European pleh₁- — to fill.

Ancestry of “πληθύω”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	πληθύς	Ionic and Epic form of πλῆθος
2	Ancient Greek	πίμπλημι	I fill; I fill myself; I am full of
3	Proto-Indo-European	pleh₁-	to fill