Where does “outubro” come from?

outubro (Old Portuguese) comes from Late Latin octobrius, from Latin octōber, from Latin octō, from Proto-Italic oktō, from Proto-Indo-European oḱtṓw, from Proto-Indo-European aḱ- — sharp, pointed; sharp, pointed, edgy; sharp,...

Ancestry of “outubro”, step by step

outubro traces back through two separate lines of ancestry.

via Late Latin octobrius

Step	Language	Word	Meaning
1	Late Latin	octobrius	—
2	Latin	octōber	of October
3	Latin	octō	eight; 8
4	Proto-Italic	oktō	eight
5	Proto-Indo-European	oḱtṓw	eight
6	Proto-Indo-European	aḱ-	sharp, pointed; sharp, pointed, edgy; sharp,...

via Latin october

Step	Language	Word	Meaning
1	Latin	october	Of October
2	Latin	octo	eight; 8

Every word from Proto-Indo-European aḱ- →Every word from Proto-Indo-European oḱtṓw →Every word from Proto-Italic oktō →