Where does “otsikoiminen” come from?

otsikoiminen (Finnish) comes from Finnish otsikoida, from Finnish otsikko, from Finnish -ikko, from Proto-Finnic -ikko, from Proto-Finnic -i- — Plural number marker in other cases than the nominative (and optionally the genitive).

Ancestry of “otsikoiminen”, step by step

StepLanguageWordMeaning
1Finnishotsikoidato title, entitle
2Finnishotsikkoheading, header, title, headline; signature
3Finnish-ikkoForms nouns for groups of a particular number,...
4Proto-Finnic-ikkoForms nouns indicating a group of things
5Proto-Finnic-i-Plural number marker in other cases than the nominative (and optionally the genitive)
Every word from Proto-Finnic -i-Every word from Finnish -ikkoEvery word from Proto-Finnic -ikko