Where does “ultimato” come from?

ultimato (Portuguese) comes from Latin ultimatum, from Latin ultimatus, from Latin ultimus, from Proto-Italic *oltm̥mos.

ultimato (Portuguese): ultimatum

Definitions

Step	Language	Word	Meaning
1	Latin	ultimatum	accusative supine of ultimō
2	Latin	ultimatus	done, finished
3	Latin	ultimus	last, final; furthest, farthest
4	Proto-Italic	*oltm̥mos	—

ultimato — Etymology, Origin & Word History | Etymology Explorer