Finnish word miksen comes from Finnish en, Finnish miksi (Why (for what cause, reason, or purpose).)

Detailed word origin of miksen

Dictionary entry	Language	Definition
en	Finnish (fin)	The first-person singular form of the negation verb. The English translations include do not/don’t and not (with auxiliary verbs and be).
miksi	Finnish (fin)	Why (for what cause, reason, or purpose).
miksen	Finnish (fin)

Words with the same origin as miksen