Asphalt, also known as bitumen (UK: / ˈ b ɪ tj ʊ m ɪ n /, US: / b ɪ ˈ tj uː m ə n, b aɪ/), is a sticky, black, highly viscous liquid or semisolid form of may be found in natural deposits or may be a refined product, and is classed as a the 20th century, the term asphaltum was also used. The word is derived from the Ancient Greek ἄσφαλτος ásphaltos.