Pronunciation: (thī'ō), [key]
containing sulfur, esp. in place of oxygen.
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meaning “sulfur,” used in chemical nomenclature in the names of compounds in which part or all of the oxygen atoms have been replaced by sulfur; often used to designate sulfur analogues of oxygen compounds.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, esp. before a vowel,thi-.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.