Finnish Adjectives | Finnish Grammar

Finnish adjectives are, mechanically, just a kind of noun. They take the same case endings, follow the same consonant gradation, and build on the same stems as nouns do. What makes them adjectives is a single extra job: when an adjective sits in front of a noun, it agrees with that noun in both case and number. There is no gender, no masculine or feminine, no separate "adjective declension" to learn — if you can decline a noun, you already know 90% of Finnish adjectives. This page is the map of the chapter; the mechanics live on the linked pages.

Adjectives decline exactly like nouns

Take iso "big." It runs through the cases with the identical endings you would put on talo "house": genitive ison, partitive isoa, inessive isossa, allative isolle. There is no adjective-specific ending anywhere in the paradigm.

Se oli iso yllätys.

It was a big surprise.

Asumme isossa talossa.

We live in a big house.

Because adjectives are declined like nouns, they also gradate like nouns. A word such as märkä "wet" loses the k of its rk cluster in the weak grade — märkä → märän → märässä — with rk behaving just as it would in any noun. Each word looks after its own gradation independently.

Koira oli märkä ja likainen.

The dog was wet and dirty.

Istuin märässä ruohossa.

I sat in the wet grass.

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There is no separate "adjective declension" to memorise. If you can put a noun into a case, you can put the matching adjective into the same case with the same ending — the two paradigms are identical. Learning Finnish nouns is learning Finnish adjectives.

Attributive agreement: the one new idea

When the adjective comes before its noun (the attributive position), it copies the noun's case and number. English adjectives never change — "big house, in the big house, big houses" — but Finnish stamps the same ending onto both words:

English	Finnish
a big house	iso talo
in a big house	isossa talossa
big houses	isot talot
in big houses	isoissa taloissa

Both words are in the inessive plural in isoissa taloissa; both are nominative plural in isot talot. This double copying — matching case and number at once — is the defining feature of Finnish adjectives and the thing English speakers forget most. It gets a full treatment on the adjective agreement page.

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Unlike French or Spanish, where an adjective agrees in number and gender, Finnish agreement is in number and case. There is no gender to match — but there are far more cases, so the ending you copy changes constantly.

Ostin punaiset kengät.

I bought red shoes.

Näin sen vanhassa valokuvassa.

I saw it in an old photograph.

Attributive vs predicative position

Agreement only applies when the adjective is attributive (in front of the noun). When it is predicative — standing after olla "to be" — it does not take the noun's case. It stays in the nominative (or, for divisible and plural subjects, the partitive). Compare:

Talo on iso.

The house is big. (predicative — nominative, not the subject's case)

Asun isossa talossa.

I live in a big house. (attributive — copies the inessive)

So the same adjective is iso after on but isossa before talossa. The split between these two positions — and the special partitive predicative in Kahvi on kuumaa "the coffee is hot" — is covered under attributive vs predicative.

The -inen family

A huge share of Finnish adjectives end in -inen: punainen "red," suomalainen "Finnish," iloinen "happy," tavallinen "ordinary." These have a special stem in -ise-: punainen → punaisen, punaista, punaisessa; suomalainen → suomalaisen, suomalaista. The dictionary form hides the stem, so these deserve their own study — see -inen adjectives.

Suomalainen sauna on kuuma.

A Finnish sauna is hot.

Puhuin iloisen naisen kanssa.

I talked with a happy woman.

Comparison: -mpi and -in

Adjectives compare with two suffixes. The comparative "more / -er" is -mpi: iso → isompi "bigger," kaunis → kauniimpi "more beautiful." The superlative "most / -est" is -in: iso → isoin "biggest," kaunis → kaunein "most beautiful." Both then decline like any other adjective and still agree with their noun.

Tämä on isompi kuin tuo.

This one is bigger than that one.

Se oli vuoden paras päivä.

It was the best day of the year.

A handful of everyday adjectives compare irregularly — hyvä → parempi → paras "good, better, best," pitkä → pidempi → pisin "long, longer, longest" — and those, with the full stem changes, are handled under the comparative.

Common mistakes

Almost every beginner adjective error is a failure to make the adjective share the noun's ending. English's invariant adjectives give you no habit of copying, so the ending gets left off.

❌ Asun iso talossa.

Incorrect — the attributive adjective must copy the inessive ending.

✅ Asun isossa talossa.

I live in a big house.

❌ Ostin punainen kengät.

Incorrect — the adjective must be plural like its noun.

✅ Ostin punaiset kengät.

I bought red shoes.

❌ Talo on isossa.

Incorrect — a predicative adjective stays nominative, not the local case.

✅ Talo on iso.

The house is big.

❌ Ostin punainen mekon.

Incorrect — the -inen adjective takes its -ise- stem and copies the ending: punaisen.

✅ Ostin punaisen mekon.

I bought a red dress.

Where to go next

Adjective agreement — the case-and-number copying, in depth, across every case.
Attributive vs predicative — when the adjective agrees and when it doesn't.
-inen adjectives — the huge -inen/-ise- class and its stems.
The comparative -mpi — "more" and "-er," including the irregulars.

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