petrochemistry(the branch of chemistry that deals with petroleum) noun [UK: ˌpe.trəʊˈk.e.mɪ.strɪ] [US: ˌpetro.ʊˈk.e.mɪ.striː]
(Nynorsk) petrokjemisk adjective
petrochemical(of or pertaining to the such compounds, or the industry that produces them) adjective [UK: ˌpe.trəʊˈk.e.mɪk.l̩] [US: ˌpetro.ʊˈk.e.mɪk.l̩]