epämuodollisissakin
The Finnish word "epämuodollisissakin" is an inflected form of the adjective "epämuodollinen" (informal). It specifically denotes a locative case, plural, and the clitic particle "kin" (also, even). Therefore, "epämuodollisissakin" translates to "even in informal ones" or "also in informal situations/settings."
This grammatical form is used when referring to something that applies or exists within informal contexts,