Where does “plup” come from?

plup (Aromanian) comes from Vulgar Latin ploppus, from Latin pōpulus, from Proto-Italic poplos — army.

plup (Aromanian): poplar

Definitions

Step	Language	Word	Meaning
1	Vulgar Latin	ploppus	poplar tree
2	Latin	pōpulus	—
3	Proto-Italic	poplos	army

plup — Etymology, Origin & Word History | Etymology Explorer