| fuel in the form of liquid or gas (synthetic natural gas) manufactured from coal or in the form of oil extracted from shale or tar sands. |
syn·fu·el  (sĭn'fyōō'əl)  n. A liquid or gaseous fuel derived from coal, shale, or tar sand, or obtained by fermentation of certain substances, such as grain. [syn(thetic) + fuel.] |
əl