a combining form meaning “tumor,” “mass,” used in the formation of compound words: oncogenic.

Origin of onco-

combining form of Greek ónkos mass, bulk
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British Dictionary definitions for onco-


combining form

denoting a tumouroncology

Word Origin for onco-

from Greek onkos
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

Medicine definitions for onco-



Mass; swelling:oncolysis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.