phe·no·thi·a·zine 
(fē′nō-thīə-zēn′, -nə-)
(fē′nō-thīə-zēn′, -nə-)n.
1. A yellow organic compound, C12H9NS, used in insecticides, livestock anthelmintics, and dyes.
2. Any of a group of drugs derived from this compound and used in the treatment of psychiatric disorders, such as schizophrenia.