Where does “aera” come from?

aera (Latin) comes from Latin aes, from Proto-Italic aos, from Proto-Italic ajos, from Proto-Indo-European h₂éyos — a metal, copper, bronze.

Ancestry of “aera”, step by step

Step	Language	Word	Meaning
1	Latin	aes	money, pay, fee, fare; copper, bronze, brass;...
2	Proto-Italic	aos	bronze, copper
3	Proto-Italic	ajos	—
4	Proto-Indo-European	h₂éyos	a metal, copper, bronze

aera — Etymology, Origin & Word History | Etymology Explorer