hiirillä

Hiirillä is the plural adessive form of the Finnish noun hiiri, meaning “mice.” In Finnish, the adessive case with -llä/-llä marks location (“on/at something”) or a means/instrument, and in the plural form hiirillä it can also express possession in combination with the verb olla (“to have”). Thus hiirillä functions both to indicate where something is and to indicate what something possesses, depending on the surrounding verb and context.

In everyday use, hiirillä is most often seen in two patterns. First, as a locative form: something happens on or at the mice, for example when talking about a setting involving mice. Second, as a possessive form with the verb olla to express “mice have.” For example, the sentence Hiirillä on suuret korvat means “The mice have large ears.” Another common usage is with a verb of action where hiirillä marks the instrument or agent in a plural sense, such as Kissa leikkii hiirillä, meaning “The cat plays with mice.”

Etymologically, hiirillä is formed by adding the adessive suffix -llä to the plural noun hiiri in its stem hiir-, reflecting standard Finnish noun- and case-formation patterns. The form is distinct from the singular adessive hiirillä (which is not used); the plural is required for the typical readings involving multiple mice.

Usage of hiirillä is most natural in descriptive or factual Finnish and appears in both everyday speech and written Finnish. It is a good example of how Finnish uses case endings to encode location, means, and possession within a single word form.