Where does “iacilium” come from?

iacilium (Vulgar Latin) comes from Latin iaciō, from Proto-Indo-European (H)yeh₁- — to throw.

Ancestry of “iacilium”, step by step

Step	Language	Word	Meaning
1	Latin	iaciō	to throw, hurl, cast, fling; throw away
2	Proto-Indo-European	(H)yeh₁-	to throw