Where does “Kartika” come from?

Kartika (English) comes from Sanskrit कार्तिक, from Sanskrit कार्त्तिक, from Sanskrit कृत्तिका, from Sanskrit -का.

Ancestry of “Kartika”, step by step

Step	Language	Word	Meaning
1	Sanskrit	कार्तिक	—
2	Sanskrit	कार्त्तिक	—
3	Sanskrit	कृत्तिका	Pleiades
4	Sanskrit	-का	—