Perustua

Perustua is a Finnish verb meaning "to be based on" or "to be founded on." It is intransitive and contrasts with perustaa, a transitive verb meaning "to establish" or "to found." Perustua is used to describe the basis or foundation of a statement, theory, or object. The verb derives from the noun perusta, meaning "base" or "foundation."

In usage, perustua appears with nouns that denote sources or grounds. Examples: "Tarina perustuu todellisiin tapahtumiin" (The story is based on real events). "Käsite perustuu tutkittuun dataan" (The concept is based on studied data). The construction often signals a justification or evidentiary basis for a claim.

Grammatical notes: Perustua is non-transitive; its forms reflect person and number in the present and past tenses and may take various case endings. In the third-person singular present tense, it appears as "perustuu" (e.g., "tulkinta perustuu uuteen tutkimukseen"), while with other subjects it agrees accordingly, such as "periaatteet perustuvat..." The past tense and passive forms are common in formal Finnish.

Etymology: From perusta "base" or "foundation" with the suffix -ua to form a verb denoting state or relation.

See also: perusta, perustaa, perustus, perustuva.

Perustua is widely used in academic, legal, and journalistic writing to indicate that a claim or conclusion rests on evidence or a principle.