Where does “ornāmentum” come from?

ornāmentum (Latin) comes from Latin ornō, from Latin ōrdnō, from Latin ōrdō, from Proto-Italic ored(h)- — to arrange.

Ancestry of “ornāmentum”, step by step

Step	Language	Word	Meaning
1	Latin	ornō	—
2	Latin	ōrdnō	—
3	Latin	ōrdō	—
4	Proto-Italic	ored(h)-	to arrange