Nominals ending with -(u)us/-(y)ys — these are mainly nouns formed from nouns and adjectives using the suffix -uus. See also type vastaus.
Inflectional stem replaces -s with -te-, which is subject to t → d consonant gradation. Before the plural marker -i-, -s is instead replaced with -ks-.
Partitive singular ending -ta/-tä, attached to the inflectional stem without the -e-, partitive plural ending -a/-ä and genitive plural ending -en.
|ends with -us
||ends with -ys
Consonant gradation detail
||t → d
Complete declension example highlighting consonant gradation (t → d)