Finnish word itse comes from Proto-Finnic *ice

Detailed word origin of itse

Dictionary entry	Language	Definition
*ice	Proto-Finnic (fiu-fin-pro)
itse	Finnish (fin)	(psychology) self, ego (as modifier in compound words) auto-, self-; see also separate entry for itse-. By -self, on/by one's own.. Oneself; used reflexively with a possessive suffix. Oneself; used to emphasize the person of the head word.

Words with the same origin as itse