According to Aikio (2020), possibly fromProto-Finnic*satu, derived from an unattested verb*sate- +-u, related toSouthern Samisoetedh(“to tell something frightening”) andSouthern Samisoete(“frightening story”). Alternatively, possibly an obscure derivation fromsattua; alternatively derived fromsataa, in which case the original meaning was "fall" and the semantic development would be comparable to that ofGermanFall(“case”) (<fallen(“to fall”)).
“satu”, inKielitoimiston sanakirja [Dictionary of Contemporary Finnish][2] (in Finnish) (online dictionary, continuously updated), Kotimaisten kielten keskuksen verkkojulkaisuja 35, Helsinki:Kotimaisten kielten tutkimuskeskus (Institute for the Languages of Finland),2004–, retrieved1 July 2023
satu in Géza Bárczi,László Országh,et al., editors,A magyar nyelv értelmező szótára [The Explanatory Dictionary of the Hungarian Language] (ÉrtSz.), Budapest: Akadémiai Kiadó, 1959–1962.Fifth ed., 1992:→ISBN.