Perustui

Perustui is the past tense form of the Finnish verb perustua, meaning “to be based on” or “to be founded.” It is used to describe something that had its basis in facts, evidence, prior work, or historical conditions. In everyday language, perustui can refer to conclusions, theories, statements, or decisions that rested on certain grounds. For example: Päätelmä perustui useisiin kokeellisiin havaintoihin. (The conclusion was based on several experimental observations.) Teoria perustui aikaisempiin tutkimuksiin. (The theory rested on earlier research.)

Grammatical notes: Perustua is intransitive, and perustui is the third-person singular past tense form. The corresponding non-past form is perustuu ("it is based on"). The transitive counterpart, perustaa, means "to establish" or "to found," as in Yritys perusti uuden toimiston. (The company established a new office.) The noun form perusta means foundation or basis, which is the semantic source of the verb.

Etymology and related terms: Perustua derives from perusta, meaning foundation or base. Related words include perusta (foundation), perustaa (to establish), and perustus (constitution or “fundamental law” in some contexts). These forms share a common notion of grounding or establishing a base for something.

See also: perustaa, perusta, perustus, perustuvia käytäntöjä. The term is primarily a grammatical form rather than a separate lexical entry, and its use depends on whether the speaker describes something as having been grounded in something else (past) or as being grounded in general (present).