Where does “tuuhentua” come from?

tuuhentua (Finnish) comes from Finnish -ua, from Proto-Finnic -üdäk — Forms mainly passive or anticausative verbs.

Ancestry of “tuuhentua”, step by step

StepLanguageWordMeaning
1Finnish-uaForms stative or inchoative intransitive verbs...
2Proto-Finnic-üdäkForms mainly passive or anticausative verbs
Every word from Proto-Finnic -üdäk →Every word from Finnish -ua →