Where does “bitūmen” come from?

bitūmen (Latin) comes from Latin -men, from Proto-Italic *-mn̥.

Ancestry of “bitūmen”, step by step

Step	Language	Word	Meaning
1	Latin	-men	forms neuter nouns of the third declension
2	Proto-Italic	*-mn̥	—

bitūmen — Etymology, Origin & Word History | Etymology Explorer