Cognomen Ounapuu (Ounapuu 
) , in the entire world, is a rare last name. The cognomen Ounapuu is characteristic of Northern Europe, particularly Estonia, where it is quite a common surname, Finland, where it is a rare surname, and Latvia. Not in comparison with a country's population, it is commonest in Estonia, Finland, and Canada. Much less frequently, Ounapuu is the forename as well as the last name.