Where does “Chaturdashi” come from?

Chaturdashi (English) comes from Sanskrit चतुर्दशी — fourteenth day in a lunar fortnight.

Ancestry of “Chaturdashi”, step by step

Step	Language	Word	Meaning
1	Sanskrit	चतुर्दशी	fourteenth day in a lunar fortnight

Chaturdashi — Etymology, Origin & Word History | Etymology Explorer