siloxane Syllabification: (si·lox·ane)Pronunciation: /siˈläksān/Definition of siloxane noun Chemistry a compound having a molecular structure based on a chain of alternate silicon and oxygen atoms, especially (as in silicone) with organic groups attached to the silicon atoms. Origin: early 20th century: blend of silicon and oxygen + -ane2siloxane in other Oxford dictionaries Definition of siloxane in the British & World English dictionary