Learn Finnish: Kansan mielipide on kansallinen salaisuus. - The nation's opinion is a national secret.

The suffix -llinen is used to turn a noun into an adjective, usually meaning 'pertaining to' or 'having the quality of' that noun. Here, it attaches to the noun kansa (nation, people) to create the adjective kansallinen (national).

What is the difference between kansan and kansallinen in this sentence?

Even though both come from kansa, they serve different grammatical roles. Kansan is the genitive (possessive) form of the noun, meaning 'the nation's' or 'of the people'. Kansallinen, on the other hand, is an adjective describing the secret, meaning 'national'.

Salaisuus looks like a derived word. How is it formed?

It is built from the adjective salainen (secret, hidden). When we turn adjectives ending in -nen into an abstract noun, the -nen changes to -s- and we add the suffix -uus. This is the same pattern you see in onnellinen (happy) becoming onnellisuus (happiness).

What are the root words for mielipide?

It is a compound word combining mieli (mind) and pide (derived from the verb pitää, meaning to hold or to keep). Literally, it translates to what your mind holds onto, which perfectly describes an opinion.