Where does “estranno” come from?

estranno (Old Portuguese) comes from Latin extraneus, from Latin -aneus, from Latin -anus, from Latin -um, from Proto-Italic *-om, from Proto-Indo-European *-oHom.

Ancestry of “estranno”, step by step

Step	Language	Word	Meaning
1	Latin	extraneus	foreign; strange; foreigner
2	Latin	-aneus	Of or pertaining to; -aneous
3	Latin	-anus	Of or pertaining to; -ian
4	Latin	-um	nominative neuter singular of -us; accusative...
5	Proto-Italic	*-om	—
6	Proto-Indo-European	*-oHom	—

Every word from Proto-Indo-European *-oHom →Every word from Latin -um →Every word from Latin -anus →