/ Dictionary / Index C Cheyenne River: Meaning and Definition of Find definitions for: Chey'enne Riv'er Pronunciation: [key] a river flowing NE from E Wyoming to the Missouri River in South Dakota. ab. 500 mi. (800 km) long. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Cheyenne Cheyne Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language