koostuu

Koostuu is a Finnish verb meaning “to consist of” or “to be made up of.” It is the third-person singular present indicative form of the intransitive verb koostua; the infinitive is koostua. The verb describes the internal makeup or composition of a thing, such as a material, a collection, or a group, rather than an action performed over time.

Grammatical notes: The subject is in the nominative, and the components are typically expressed by a noun phrase in the elative case (ending in -sta/-stä), for example kahdesta osasta or proteiineista. The past tense is koostui. The perfect is formed with the auxiliary on and the past participle: on koostunut. The verb is intransitive, so the focus is on what the thing comprises rather than an external agent performing an addition.

Usage examples:

Ravinto koostuu pääasiassa proteiineista ja hiilihydraateista.

Kokoelma koostuu useista tunnetuista teoksista.

Tiimi koostuu sekä kokeneista että uusista jäsenistä.

Usage notes: Koostua is used to describe the makeup or components of something, including scientific, technical, and everyday contexts. It is often chosen over verbs that emphasize a dynamic process of forming, depending on whether the emphasis is on the ends result rather than the act of assembly. Etymologically, koostua is a native Finnish verb with cognates within Finnic languages, and it remains a common, general expression for describing composition. See also Finnish grammar and the verb formada related terms for related concepts in description of structure and composition.