Where does “viistokaiku” come from?

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

Ancestry of “viistokaiku”, step by step

viistokaiku traces back through two separate lines of ancestry.

via Finnish kaiku

StepLanguageWordMeaning
1Finnishkaikuecho
2Finnishkaikuato echo, reverberate; Partitive singular form...
3Finnish-uaForms stative or inchoative intransitive verbs...
4Proto-Finnic-üdäkForms mainly passive or anticausative verbs

via Finnish viisto

StepLanguageWordMeaning
1Finnishviistooblique, slanting, inclined; slanted; diagonal
2FinnishviistääTo bevel
Every word from Proto-Finnic -üdäk →Every word from Finnish -ua →Every word from Finnish kaikua →