thio-

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“sulfur,” used in chemical nomenclature in the names of compounds in which part or all of the oxygen atoms have been replaced by sulfur; often used to designate sulfur analogues of oxygen compounds.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

combining form representing Greek theîon

British Dictionary definitions for thio-

thio-

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 atom: thiol, thiosulphate

Word Origin

from Greek theion sulphur

thio- in Medicine

thio- or thi-
pref.
Containing sulfur, used especially of a compound in which oxygen has been replaced by a divalent sulfur: thioacid.

thio- in Science

thio- or thi-
A prefix that means "containing sulfur," used especially of a compound in which an oxygen atom has been replaced by a sulfur atom, as in thiourea.