Learn Finnish: Tanssijan kasvot ovat todella ilmekkäät. - The dancer's face is very expressive.

It is derived from the noun ilme (expression, look). By adding the suffix -käs, we get ilmekäs, meaning expressive or full of expressions. Because of vowel harmony with the front vowels in ilme, we use the version -käs instead of -kas.

Why is there a double k in ilmekkäät if the base word is ilmekäs?

Adjectives ending in -kas or -käs undergo a specific stem change. The dictionary form has a single k, but when you add an ending like the plural marker -t, the stem switches to the strong grade, doubling the consonant to kk. The final vowel also lengthens, making the plural stem ilmekkää- before adding the -t.

The English translation says 'face is', so why does the Finnish sentence use the plural verb ovat?

In Finnish, the word for face, kasvot, is always a plural noun, much like the English words 'scissors' or 'glasses'. Because the subject kasvot is plural, the verb must be the plural ovat, and the describing adjective must also match in the plural form, which is why we use ilmekkäät.

As a refresher, how do we build the word tanssijan?