[ thahy-oh ]
/ ˈθaɪ oʊ /

adjective Chemistry.

containing sulfur, especially in place of oxygen.



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Origin of thio

independent use of thio-

Definition for thio (2 of 2)


a combining form meaning “sulfur,” used in chemical nomenclature in the names of compounds in which part or all of the oxygen atoms have been replaced by sulfur; often used to designate sulfur analogues of oxygen compounds.
Also especially before a vowel, thi-.

Origin of thio-

combining form representing Greek theîon Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for thio

  • Alum does not agree with the thio dyestuffs which are manufactured by Dahl & Co., Barmin, and are fast against soap and light.

British Dictionary definitions for thio


before a vowel thi-

combining form

indicating that a chemical compound contains sulphur, esp denoting that a compound is derived from a specified compound by the replacement of an oxygen atom with a sulphur atomthiol; thiosulphate

Word Origin for thio-

from Greek theion sulphur
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

Medical definitions for thio



Containing sulfur, used especially of a compound in which oxygen has been replaced by a divalent sulfur:thioacid.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for thio


A prefix that means “containing sulfur,” used especially of a compound in which an oxygen atom has been replaced by a sulfur atom, as in thiourea.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.