- a mineral coal that contains volatile hydrocarbons and tarry matter and burns with a yellow, smoky flame; soft coal.
- a soft black coal, rich in volatile hydrocarbons, that burns with a smoky yellow flame. Fixed carbon content: 46–86 per cent; calorific value: 1.93 × 10 7 – 3.63 × 10 7 J/kgAlso called: soft coal
- A soft type of coal that burns with a smoky, yellow flame. Bituminous coal is the most abundant form of coal. It has a high sulfur content, and when burned, gives off sulfurous compounds that contribute to air pollution and acid rain. Compare anthracite lignite.