Noun oto has 2 senses
- Oto, Otoe - a member of the Siouan people inhabiting the valleys of the Platte and Missouri rivers in Nebraska
--1 is a kind of Sioux, Siouan
- Oto, Otoe - a dialect of the Chiwere language spoken by the Oto people
--2 is a kind of Chiwere
,