Where does “quanta” come from?

quanta (Latin) comes from Latin quantus, from Proto-Italic *kʷijentos, from Proto-Indo-European *kʷíh₂onts.

quanta (Latin): nominative feminine singular of quantus;...

Definitions

Step	Language	Word	Meaning
1	Latin	quantus	how much, how many; how big
2	Proto-Italic	*kʷijentos	—
3	Proto-Indo-European	*kʷíh₂onts	—

quanta — Etymology, Origin & Word History | Etymology Explorer