Of fuel gas: of low calorific value.

Of natural gas: containing significant amounts of the vapour of higher hydrocarbons.

Transformed into a liquid state; spec. (of a solid) molten; (of a gas) made liquid by cooling or compression (now frequently in liquefied natural gas…

Old Chemistry and Metallurgy. Free from corrosive salt, sulphur, acid, etc. In modern use also in the Oil Industry, of petroleum or natural gas…