perusteeseen

Perusteeseen is the illative singular form of the Finnish noun peruste, meaning "basis" or "foundation." The illative case expresses movement toward or into a destination and is used with verbs and contexts that denote entering a place, a state, or a figurative domain. In the sense of entering a basis or foundation, perusteeseen can appear in theoretical or technical language.

Form and related forms: peruste is the nominative singular. Its genitive singular is perusteen. Other common cases include inessive perusteessa (in the basis), elative perusteesta (from the basis), allative perusteelle (to the basis), essive perusteena (as a basis), translative perusteeksi (into a basis), and partitive perustetta (a basis, some basis). The illative plural is perusteisiin (into bases).

Usage: The illative perusteeseen is relatively specialized and primarily occurs in formal, academic, or technical writing. It is less common in everyday speech, where related ideas are often expressed with other constructions such as perusteen mukaan (according to the basis) or using other cases to denote location or state. The illative form is most natural when describing movement into a conceptual or physical basis as part of a larger description of change, transition, or progression.

See also: Finnish grammar, illative case, peruste.