petroleum jelly
noun [ U ] uk/pəˌtrəʊ.li.əm ˈdʒel.i/ us/pəˌtroʊ.li.əm ˈdʒel.i/
石油冻，矿脂
a clear substance made from petroleum, used as a base for medicines that are rubbed into the skin, and also for making parts in a machine move easily against each other