mouhi- + järvi, possibly from the dialectal word mouhu(“small fish”), albeit this is uncertain since the word is only found in Eastern dialects, not near Satakunta.[1]
The external locative cases (adessive, allative and ablative) are used with this place name when referring to a location; for example, "in Mouhijärvi" is Mouhijärvellä.
^ Sirkka Paikkala, editor (2007), Suomalainen paikannimikirja [The Book of Finnish Place Names] (in Finnish), Helsinki: Karttakeskus, Kotimaisten kielten tutkimuskeskus, →ISBN