Where does “vakaisuus” come from?

vakaisuus (Finnish) comes from Finnish vakainen, from Finnish -inen, from Finnish -uus, from Proto-Finnic -uc — -ness, -hood.

Ancestry of “vakaisuus”, step by step

StepLanguageWordMeaning
1FinnishvakainenSynonym of vakaa
2Finnish-inen-like, -ous, -y; -en; Creates adjectives from...
3Finnish-uusForms nouns from adjectives, expressing a quality
4Proto-Finnic-uc-ness, -hood
Every word from Proto-Finnic -uc →Every word from Finnish -inen →Every word from Finnish -uus →