[ thahy-oh ]

  1. containing sulfur, especially in place of oxygen.

Origin of thio

Independent use of thio-

Other definitions for thio- (2 of 2)


  1. 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meaning “sulfur,” used in chemical nomenclature in the names of compounds in which part or all of the oxygen atoms have been replaced by sulfur; often used to designate sulfur analogues of oxygen compounds.

Origin of thio-

Combining form representing Greek theîon
  • Also especially before a vowel, thi-. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use thio in a sentence

  • We may also notice that thio-ethers combine with alkyl iodides to form sulphine or sulphonium compounds, R3SI.

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

  • The sulpho-acid of the thio-base is a yellow dye, which was named by its discoverer “primuline.”

    Coal | Raphael Meldola

British Dictionary definitions for thio-


combining form
  1. 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 atom: thiol; thiosulphate

Origin of 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

Scientific definitions for thio-


  1. A prefix that means “containing sulfur,” used especially of a compound in which an oxygen atom has been replaced by a sulfur atom, as in thiourea.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.