Creating Adjectives with "-llinen"
Finnish has a productive suffix for turning nouns into adjectives: -llinen. It works much like the English suffixes "-al", "-ic", or "-ly".
To form the adjective, attach -llinen to the noun's inflectional stem. This is the same base you use for the genitive case, meaning the noun will undergo consonant gradation if applicable.
For example, kansa (nation) simply becomes kansallinen (national).
For nouns ending in -e (like tiede, science), the stem ends in -ee-. Remember to apply consonant gradation (here, the weak d strengthens to t), giving us tieteellinen (scientific).
Society and Nature
The word for society, yhteiskunta, weakens its nt to nn in the stem, producing yhteiskunnallinen (societal). Likewise, luonto (nature) undergoes the same nt to nn change to become luonnollinen (natural).
Spoken and Written Rules
You will frequently see -llinen used for methods of communication and legal concepts. From basic nouns, we get essential adjectives:
- kirja (book) -> kirjallinen (written)
- suu (mouth) -> suullinen (oral)
- laki (law) -> laillinen (legal)
Arts and Language
Finally, you can describe creative or linguistic qualities using the exact same pattern. Notice how the words for art (taide) and language (kieli) use their inflectional stems (taitee- and kiele-) before adding the suffix.