/ Dictionary / Index Y Yerkes: Meaning and Definition of Find definitions for: Yer•kes Pronunciation: (yûr'kēz), [key] — n. 1837–1905, U.S. financier and mass-transit magnate. 1876–1956, U.S. psychologist and psychobiologist: pioneered in studies of the great apes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: yerkes (Thesaurus) yerk Yerkes Observatory Related Content Daily Word Quiz: respite Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language