The short answer
A Swedish adjective has three forms and no more. With an en-word it is bare: en stor bil. With an ett-word it takes -t: ett stort hus. In the plural, and in every definite phrase, it takes -a: stora bilar, den stora bilen, det stora huset, de stora bilarna. The -a form also follows a possessive: min stora bil.
Swedish adjectives change form based on the gender (en/ett) and number of the noun, and whether the noun is definite or indefinite.
Indefinite: en stor bok, ett stort hus, stora böcker. Definite: den stora boken, det stora huset, de stora böckerna.
The three forms of stor (big)
| Context | Form | Example |
|---|---|---|
| en-word, indefinite | stor | en stor bil |
| ett-word, indefinite | stort | ett stort hus |
| plural, indefinite | stora | stora bilar |
| en-word, definite | stora | den stora bilen |
| ett-word, definite | stora | det stora huset |
| plural, definite | stora | de stora bilarna |
| after a possessive | stora | min stora bil |
Adjectives that do not follow the pattern
| Adjective | en | ett | Plural / definite | Meaning |
|---|---|---|---|---|
| liten | liten | litet | små / lilla | small |
| gammal | gammal | gammalt | gamla | old |
| ny | ny | nytt | nya | new |
| blå | blå | blått | blåa / blå | blue |
| bra | bra | bra | bra | good (never changes) |
In a sentence
en stor bil (en, indef.)
a big car
ett stort hus (ett, indef.)
a big house
stora bilar (plural)
big cars
den stora bilen (definite)
the big car
What learners get wrong
ett stor hus
Say instead: ett stort hus
An ett-word pulls -t onto the adjective. This is the most frequent single agreement error, because the noun looks unchanged.
den stor bilen
Say instead: den stora bilen
Everything definite takes -a, whatever the gender. Definite is simpler than indefinite: one ending covers all three cases.
Questions people ask
- Do all adjectives take -t for ett-words?
- Almost all, but a few resist. Adjectives already ending in -t often stay put, bra never changes at all, and some ending in -isk (praktisk → praktiskt) or in a vowel behave irregularly. The pattern covers the vast majority; the exceptions are a short list worth learning as words.
- Why is it den stora bilen and not den stor bilen?
- Because the definite form of the adjective is -a across the board. Swedish marks definiteness three times over in that phrase — the front article den, the adjective ending -a, and the suffix -en on the noun. All three are required.
- What happens after min, din, hans?
- The adjective takes the definite -a even though there is no article: min stora bil, hans nya hus, deras gamla hund. A possessive makes the phrase definite, and the adjective follows.
Sources
Usage checked against Isof, the Swedish government's language institute, and Svenska Akademien. Where usage is genuinely divided, this page says so rather than inventing a rule.