Perustuivat

Perustuivat is a Finnish verb form. It is the imperfect (past) tense of perustua in the third-person plural, and it generally translates as “they were based (on)” or “they based themselves.” The verb perustua is intransitive and is used to indicate that something has its basis in another thing, belief, rule, or previous event. The contrast with perustaa, which is transitive and means “to establish” or “to found,” is important: perustaa describes creating something, whereas perustua describes the basis or foundation of something already existing.

In usage, perustuivat commonly appears in historical, analytical, and descriptive prose to describe the basis or origins of actions, policies, institutions, or ideas in the past. It is often followed by a phrase naming the basis, such as old principles, evidence, or data. For example, hankkeet perustuivat vanhoihin periaatteisiin means “the projects were based on old principles.” The form is also used to discuss shifts in basis over time. In contexts where the subject is a single entity or where the action is to establish something, the related form perustettiin (passive past) is often used to indicate “was/were founded.”

Etymology and related forms: perustua comes from the root perust-, with typical Finnish verb morphology. Related verbs include perustaa (to establish/found) and perustus (foundation). Perustuva or perustuvaan are other derived forms used in different moods or constructions.