Heating Value - Definition, Glossary, Details - Oilgae
The amount of heat produced by the complete combustion of a given amount of fuel - Source
The amount of heat produced from the complete combustion of a unit of fuel. The higher (or gross) heating value is that when all products of combustion are cooled to the pre-combustion temperature, water vapor formed during combustion is condensed, and necessary corrections have been made - Source
The heating value or calorific value of a substance, usually a fuel or food, is the amount of heat released during the combustion of a specified amount of it - Wikipedia