1) Ally of the Missouri 2) American indian 3) Bison-hunting tribe 4) Buffalo-hunting tribe 5) Certain Oklahoman 6) Certain plains native 7) Certain siouan 8) Chiwere dialect 9) Chiwere speaker 10) Combining form for ear 11) Ear opening 12) Ear prefix 13) Ear-related prefix 14) Ear-relevant opener 15) Ear-relevant prefix Found on https://www.crosswordclues.com/clue/oto
North American Indian people of the Chiwere branch of the Siouan linguistic family, which also includes the closely related Missouri and Iowa tribes. ... Found on http://www.britannica.com/eb/a-z/o/38
[n] - a member of the Siouan people inhabiting the valleys of the Platte and Missouri rivers in Nebraska 2. [n] - a dialect of the Chiwere language spoken by the Oto people Found on http://www.webdictionary.co.uk/definition.php?query=Oto
a member of a Siouan-speaking tribe of North American Indians who formerly inhabited the lower Missouri River basin and now live in Oklahoma. Found on https://www.infoplease.com/dictionary/oto