Where does “Enero” come from?

Enero (Bikol Central) comes from Spanish enero, from Old Spanish janero, from Vulgar Latin ienuārius, from Latin iānuārius, from Latin -ārius, from Proto-Italic *-āzios — Forms relational adjectives to nouns (and rarely numerals).

Ancestry of “Enero”, step by step

Step	Language	Word	Meaning
1	Spanish	enero	January
2	Old Spanish	janero	January
3	Vulgar Latin	ienuārius	—
4	Latin	iānuārius	of January
5	Latin	-ārius	er
6	Proto-Italic	*-āzios	Forms relational adjectives to nouns (and rarely numerals)

Every word from Proto-Italic *-āzios →Every word from Latin -ārius →Every word from Latin iānuārius →