Where does “lur” come from?

lur (Old Catalan) comes from Vulgar Latin *illūrum, from Latin illōrum, from Proto-Indo-European h₂él-.

Ancestry of “lur”, step by step

Step	Language	Word	Meaning
1	Vulgar Latin	*illūrum	—
2	Latin	illōrum	—
3	Proto-Indo-European	h₂él-	—