Where does “trentel” come from?

trentel (Old French) comes from Latin trigintale, from Latin triginta, from Proto-Indo-European tri(d)ḱomt — thirty; three-ten.

Ancestry of “trentel”, step by step

Step	Language	Word	Meaning
1	Latin	trigintale	—
2	Latin	triginta	thirty; 30
3	Proto-Indo-European	tri(d)ḱomt	thirty; three-ten

trentel — Etymology, Origin & Word History | Etymology Explorer