Matter in a state intermediate between liquid and plasma that can be contained only if it is fully surrounded by a solid (or in a bubble of liquid) (or held together by gravitational pull); it can condense into a liquid, or can (rarely) become a solid directly.
A flammable gaseous hydrocarbon or hydrocarbon mixture (typically predominantly methane) used as a fuel, e.g. for cooking, heating, electricity generation or as a fuel in internal combustion engines in vehicles.