mazut
/məˈzuːt/(also masut, mazout, mazute)
noun
In Russia: a viscous liquid left as a residue after the distillation of petroleum, used as a fuel oil and coarse lubricant.
Origin
Late 19th century; earliest use found in Chambers's Journal of Popular Literature. From Russian mazut fuel oil, perhaps from an Azerbaijani Turkish derivative ultimately of Arabic zayt oil (plural zuyūt); probably unrelated to Russian regional mazutina oily stain (Tver′ region, 1897), Russian mazat′ to oil, to smear.