Inessiivimuodot

Inessiivimuodot, or inessive forms, are the Finnish noun inflections that express location inside something. They form one of the locative case forms and are used to indicate that something is “in” or within a container, place, or object. In everyday Finnish, they appear with nouns referring to places, objects, or general domains where a location is described.

Formation and variants: The inessive forms are built with suffixes. In singular, the common endings are -ssa or -ssä, while in plural they are -issa or -issä. Which variant is used depends on vowel harmony: words whose stem ends in a back vowel (a, o, u) take -ssa, and those ending in a front vowel (ä, ö, y, i, e) take -ssä. The plural suffix adds an -i- before the final -ssa/ -ssä, yielding endings like -issa/-issä. Examples include talo -> talossa (in the house) and talot -> taloissa (in the houses); vesi -> vedessä (in the water) and vedet -> vesissä (in the waters). Some words may undergo minor stem changes or consonant gradation when forming these endings.

Usage and notes: Inessiivimuodot are used with verbs of location or existence, such as olla or asua, to describe where something is located (for example, Hän on talossa — He is in the house). They are part of a set of locative cases in Finnish and contrast with other cases like elative (out of), illative (into), adessive (on/at), and allative (onto). While the basic pattern covers most nouns, irregulars and stems with unusual phonology may show nonstandard forms.