adjektiviin

Adjektiviin is the illative singular form of the Finnish noun adjektiivi, meaning “into the adjective.” It is a grammatical form that appears in linguistic descriptions and grammar references, rather than in everyday speech.

In Finnish, the illative case marks direction into something or into a state, and adjektiivi in illative is created by adding the appropriate illative suffix to the stem. The noun adjektiivi refers to the concept of an adjective, so adjektiiviin is primarily encountered in meta‑linguistic or educational contexts when discussing how adjectives can be treated as a noun and inflected like other words.

Usage of adjektiiviin outside standard prose is rare; it is mainly used in dictionaries, grammar texts, or examples that illustrate the behavior of inflectional endings on words derived from adjectives. Because it concerns linguistic terminology rather than common communication, it does not play a large role in ordinary sentences.

See also: Finnish grammar, illative case, noun inflection, adjectives in Finnish.