The term 'burner output' can be summarized as the amount of GAS that is produced by a burner. The crossword solution for this term is GAS, which is an abbreviation for the chemical compound known as 'gaseous hydrocarbons'. This type of GAS is often used in industrial and commercial applications, such as heating, cooking, and powering machinery. Burner output is typically measured in BTUs (British Thermal Units) or cubic feet per hour.