Reconstruction:Proto-Finnic/-o

From Proto-Uralic *-w, originally specifically when attached to *-a- stems (as opposed to *-u), but this system broke down by Proto-Finnic and both suffixes could be used with any vowels (with less of an apparent pattern), although a tendency may have remained.

*-o

1. Forms action/result nouns from verbs.
2. Forms mainly diminutive nouns from nominal stems.

• Finnish: -o (merged with *-oi)
• Ingrian: -o

• Hakulinen, Lauri. 1941–2000. Suomen kielen rakenne ja kehitys ('The Structure and Development of the Finnish Language'). Helsinki: Otava/Helsingin yliopisto.