/ Dictionary / Index R rheotron: Meaning and Definition of Find definitions for: rhe•o•tron Pronunciation: (rē'u-tron"), [key] — n. Physics. (formerly) betatron. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rheotaxis rheotropism Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language