muuttujin

Muuttujin is a Finnish inflected form of the noun muuttuja, which means "variable" (a thing that changes or a symbol whose value may vary). The form muuttujin corresponds to the instructive case and is used to indicate means, manner or instrumentality, roughly translating to "by/with variables" or "using variables" in English.

In technical and mathematical language, muuttujin appears in expressions that describe operations or representations performed by means of variables, for example "esitetään muuttujin" ("is expressed using variables") or "laskenta muuttujin" ("calculation by variables"). The instructive case is relatively common in written and formal Finnish in constructions that emphasize the method or tool used.

Etymology and formation: muuttuja derives from the verb muuttaa ("to change") with the agentive suffix -ja, forming a noun for an entity that changes or causes change. The instructive plural ending -in attaches to produce muuttujin. Usage of this case is more frequent in set phrases and formal contexts than in everyday spoken Finnish, where other constructions (e.g., using the adessive with kanssa or the elative/ablative) may be preferred.

Related forms include muuttujat (nominative plural), muuttujan (genitive singular) and muuttujia (partitive plural).