loanword from one of the now-extinct Saami languages once spoken in the area.
The most probable theory is that the name derives from the Finnish dialectal word oulu, meaning "floodwater", which is related to e.g. Southern Saami åulo, meaning "melted snow", åulot meaning "thaw" (of unknown ultimate origin). Two other word families have also been speculated to be related. The first is seen in the Northern Savo dialectal word uula and its Saami counterpart oalli, both meaning "river channel". The second is the Uralic root reconstructed as *uwa, meaning "river bed" (reflected as vuo in modern Finnish, also in derivatives such as vuolas "heavy-flowing"). To either of these roots, some Saami variety would have to be assumed having added further derivational suffixes
