a combining form meaning “flow,” “current,” “stream,” used in the formation of compound words: rheoscope.

Compare -rrhea.

Origin of rheo-

combining form representing Greek rhéos stream, something flowing
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for rheo-


combining form

indicating stream, flow, or currentrheometer; rheoscope

Word Origin for rheo-

from Greek rheos stream, anything flowing, from rhein to flow
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for rheo-

word-forming element meaning "current of a stream," from Greek rheos "a flowing, stream, current," from PIE root *sreu-; see rheum.

Online Etymology Dictionary, © 2010 Douglas Harper

rheo- in Medicine



Current; flow:rheotaxis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.