käyttöjärjestelmällään

Käyttöjärjestelmällään is a Finnish grammatical form built from käyttöjärjestelmä (operating system) combined with the instrumental/adessive suffix -llä and the third-person possessive suffix, yielding a single word that typically translates to “with his/her/its operating system” or “on his/her/its operating system,” depending on context. It illustrates how Finnish can encode possession and means within one word.

Morphology and meaning: The base noun käyttöjärjestelmä denotes an operating system. The -llä suffix marks instrumentality or locale (with/on). The possessive aspect attached to the form indicates the possessor (his/her/its). The resulting form, käyttöjärjestelmällään, thus signals that an action or state involves the operating system belonging to someone, without repeating the possessor explicitly in the sentence.

Usage: The form is most common in technical or formal writing where it is natural to specify that something is done with or on a particular OS owned by a subject. It helps to avoid repetition, especially when the possessor is already established in the discourse. In everyday speech, speakers may rephrase to explicit possessive phrases such as omalla käyttöjärjestelällään or their OS, depending on clarity and formality.

Example: Sovellus toimii parhaiten käyttöjärjestelmällään. Translation: The application runs best on its operating system (i.e., on the OS belonging to the subject). Note that the exact possessor is determined by context, and similar meanings can be conveyed with alternative constructions if needed.

See also: Finnish morphology, instrumental case, possessive suffixes, compound formation in Finnish.