/ Dictionary / Index Y Yanktonai: Meaning and Definition of Find definitions for: Yank•to•nai Pronunciation: (yangk"tu-nī'), [key] — pl. -nais, -nai. a member of one of two tribes of Dakota Indian people who inhabited the northern Great Plains in the 18th and 19th centuries. Cf.(def. 1). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Yankton Yannina Related Content Daily Word Quiz: tenacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language