English Etymology Due to the smell it gives off when burned. Noun dirty coal (uncountable) (informal) lignite 1978 February 14, “Texas Turning to Its Reserves of Lignite”, in New York Times:Lignite's nickname “dirty coal,” suggests its one major drawback, but its allure is clearly its cost. Lignite is cheaper than most other energy sources. Wikiwand - on Seamless Wikipedia browsing. On steroids.