Where does “obertura” come from?

obertura (Vulgar Latin) comes from Latin apertura, from Latin apertus, from Latin aperiō, from Proto-Indo-European h₂epó — off, away.

Ancestry of “obertura”, step by step

Step	Language	Word	Meaning
1	Latin	apertura	an opening, hole, aperture; an opening;...
2	Latin	apertus	opened, open, free; public; having been opened;...
3	Latin	aperiō	to uncover, make or lay bare, reveal, clear
4	Proto-Indo-European	h₂epó	off, away