Perusmuoto

Perusmuoto, literally "base form" in Finnish, is a linguistic term used to describe the canonical base form of a word. It functions as the dictionary form or lemma and serves as the reference point from which other inflected forms are derived. In practice, perusmuoto is the form you would typically find as the headword in a Finnish dictionary, and it is the form used in language learning and linguistic analysis for conjugation and declension.

For verbs, the perusmuoto is usually the active infinitive, ending in -a/-ä or -ta/-tä, such as kirjoittaa or syödä. From this form, the full set of verb forms in different tenses, moods and persons is generated by applying endings and occasional stem changes.

For nouns, the perusmuoto is commonly the nominative singular. This form serves as the starting point for forming other cases (like genitive and partitive) and for inflection across number and case.

For adjectives, the perusmuoto is typically the positive form in singular, from which inflections for degree, comparison and grammatical cases are derived.

In modern usage, perusmuoto is closely related to the linguistic concepts of lemma and headword, and it is widely used in computational linguistics for tasks such as lemmatization. Etymologically, perusmuoto combines perus "base, fundamental" with muoto "form," underscoring its role as the foundational form of a word.