Adjectives With a Partitive

The partitive case is used in several distinct ways involving adjectives and related words:

1. Adjective Agreement (Congruence)
In Finnish, adjectives must agree with the noun they modify. If a noun is in the partitive, the adjective must also be in the partitive:

• kaksi isoa koiraa (two big dogs)
• Luen mielenkiintoista kirjaa. (I am reading an interesting book.)

2. Plural Predicative Adjectives
When the subject of an olla sentence is plural, the adjective describing it is almost always in the plural partitive:

• Omenat ovat makeita. (The apples are sweet.)
• Nuo autot ovat nopeita. (Those cars are fast.)

For a pair or an inherently plural whole, a nominative plural predicative can describe the set as a unit:

• Nämä kengät ovat uudet. (These shoes are new.)
• Sakset ovat terävät. (The scissors are sharp.)

3. Adverbs and Adpositions Governing the Partitive
Certain adjective-like words, adverbs, or adpositions of state require the partitive. Note that these are not true adjectives and do not inflect like them:

• täynnä (full of): Lasi on täynnä vettä.
• vailla (without): Olen vailla rahaa.

4. Partitive of Comparison
When comparing two things without using kuin (than), the thing you are comparing against must be in the partitive and placed before the comparative adjective:

• Hän on minua vanhempi. (He is older than me.)

5. Predicative Adjectives with Mass Nouns, Abstract Nouns, Infinitives, and Impersonal Sentences
Unlike singular countable objects which take the nominative (e.g., Talo on iso.), when an adjective describes a mass noun (uncountable substance), an abstract noun, or an infinitive/subclause subject in a sentence with olla, the adjective is usually in the partitive when the subject is construed as unbounded or divisible:

• Tee on kuumaa. (The tea is hot.)
• Rakkaus on vaikeaa. (Love is difficult.)
• Uiminen on hauskaa. (Swimming is fun.)

This also applies to impersonal sentences that lack a formal subject (where English uses a dummy 'it' or 'there'). In these sentences, the predicative adjective is typically in the partitive singular:

• Täällä on hiljaista. (It is quiet here.)
• Ulkona on pimeää. (It is dark outside.)

Note that abstract nouns take the nominative when conceptualized as a specific, bounded entity or a complete whole:

• Tämä päätös on vaikea. (This decision is difficult.)

Weather words are not an absolute exception: Sää on tuulinen and Sää on tuulista are both standard, with a different construal. A bounded description also uses nominative, as in:

• Sää on kaunis. (The weather is beautiful.)
• Taivas on sininen. (The sky is blue.)

6. Indefinite Pronouns
Adjectives modifying indefinite pronouns like jotain (something) or mitään (anything) are also in the partitive:

• Haluatko jotain makeaa? (Do you want something sweet?)

7. Numerals
In an ordinary nominative numeral phrase with a cardinal above one, the following noun and modifying adjective are partitive singular. Other case forms require separate agreement rules:

• kolme pientä kissaa (three small cats)

8. Negative Sentences
In negative transitive sentences, the object and its modifying adjective must be in the partitive:

• En osta uutta autoa. (I am not buying a new car.)

Negation Does Not Turn a Predicative Into an Object
Talo on iso → Talo ei ole iso. A singular countable subject still normally has a nominative adjective after negation; do not say Talo ei ole isoa for this meaning. In contrast, En osta isoa taloa has a negative object, which is partitive. A mass-noun predicative remains partitive: Kahvi ei ole kuumaa. Also distinguish täynnä vettä from the adjective arvoinen, whose complement is genitive: kiitoksen arvoinen (worthy of thanks).