Where does “aunclum” come from?

aunclum (Vulgar Latin) comes from Latin avunculus, from Proto-Indo-European h₂éwh₂os — maternal grandfather; maternal uncle.

Ancestry of “aunclum”, step by step

Step	Language	Word	Meaning
1	Latin	avunculus	maternal uncle, mother's brother; mother's...
2	Proto-Indo-European	h₂éwh₂os	maternal grandfather; maternal uncle

aunclum — Etymology, Origin & Word History | Etymology Explorer