Where does “vulgaris” come from?

vulgaris (Latin) comes from Latin -āris, from Latin -ālis, from Proto-Italic -ālis.

Ancestry of “vulgaris”, step by step

Step	Language	Word	Meaning
1	Latin	-āris	—
2	Latin	-ālis	—
3	Proto-Italic	-ālis	—

vulgaris — Etymology, Origin & Word History | Etymology Explorer