The nominative is the case of a subject of a clause and has no ending in the singular. In plural it has the ending t (e.g. talo : talot), whereas in all other cases, the plural suffix is i or j, appearing before the case suffix (e.g. taloissa). Thus, the suffix t can be interpreted as indicating both the case and the number. Apart from this, the nominative has no case suffix.
The nominative singular often has a form different from the stem of all other cases, e.g. hevonen (horse) as opposite to other cases that start with hevose- or hevos-. However, this is interpreted as stem variation.
The nominative is used as the case of the subject and under certain conditions as the case of an object (see Marking the object). For example, in the sentence Minä söin omenat (I ate the apples), the subject minä is in nominative singular, the object omenat is in nominative plural.
The subject can also appear in the partitive case.
The nominative is also used in title texts, labels, lists, etc., when there is no reason to use an inflected form. However, in package texts, the partitive is also used, e.g. Herneet ∼ Herneitä (peas).
The nominative is used in informal language for the unit when expressing unit costs, e.g. viisi euroa kilo (five euros per kilo). The correct way in standard language is to use the ablative, e.g. viisi euroa kilolta.
The nominative is also used in expressions such as ase kädessä (weapon in hand) in the statement Hän käveli ase kädessä (He walked with a weapon in his hand). Such expressions are called, somewhat misleadingly, absolute nominative. The point is that the nominative form of a noun is used as part of an adverbial together with other words, describing the location, state etc. This distinguishes the construct from a subject in the nominative. Usually the subject is easy to distinguish from an absolute nominative, since the subject normally appears first, but for poetic reasons or for emphasis, we can say e.g. Ase kädessä hän taisteli meitä vastaan (By force of arms he fought against us).
The “absolute nominative” typically corresponds to a phrase using the “with” preposition in English. Note the lack of any possessive suffix here, even though we would say Hänellä oli ase kädessään (He had a weapon in his hand), where ase is a predicative.