katsetust

Katsetust is an Estonian grammatical form and lexical concept related to testing and experimentation. Linguistically, it is the partitive singular of the noun katsetus, which itself is derived from the root katse (meaning "test" or "experiment") with the nominalizing suffix -tus; in translation katsetust corresponds to "testing", "experimentation" or "a trial" in contexts where partitivity or indefiniteness is expressed.

In Estonian grammar the partitive case is used to denote incomplete actions, ongoing processes, indefinite quantities, or objects of negation, so katsetust appears where a speaker wishes to convey an unspecified amount or continuation of testing. As a lexical item, katsetust is used in scientific, technical and everyday contexts to refer to experiments, trials, product testing, pilot studies and iterative trial-and-error work.

Related words include katse (test), katsetamine (the gerund "testing"), and testimine (a direct calque from "testing"). In translations and technical writing, katsetust is often rendered as testing or experimentation, with nuance depending on syntactic context. The term is common in both written and spoken Estonian when discussing research procedures, quality assurance, prototype evaluation and experimental methods.