thio-

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“sulfur,” used in chemical nomenclature in the names of compounds in which part or all of the oxygen atoms have been replaced by sulfur; often used to designate sulfur analogues of oxygen compounds.

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 atomthiol; thiosulphate

pref.

1. Containing sulfur, used especially of a compound in which oxygen has been replaced by a divalent sulfur:thioacid.

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 A prefix that means “containing sulfur,” used especially of a compound in which an oxygen atom has been replaced by a sulfur atom, as in thiourea.