ssäloppuinen
"ssäloppuinen" is a Finnish language term that describes a word or phrase ending in the Finnish inessive case suffix "-ssä". The inessive case is one of the Finnish locative cases and typically indicates location "in" or "inside" something. Therefore, words that are "ssäloppuinen" are those that are inflected with this particular suffix.
For example, the word "talo" means "house". When inflected into the inessive case, it becomes "talossa", meaning
The "-ssä" suffix is attached to the stem of a noun, adjective, or pronoun, undergoing stem changes