thiourea Syllabification: (thi·o·u·re·a)Pronunciation: /ˌTHī-ōyəˈrēə/Definition of thiourea noun Chemistry a synthetic crystalline compound used in photography and the manufacture of synthetic resins. The sulfur analog of urea; chemical formula: SC(NH2)2 thiourea in other Oxford dictionaries Definition of thiourea in the British & World English dictionary