- fine particles of ash of a solid fuel carried out of the flue of a furnace with the waste gases produced during combustion.
- such ash recovered from the waste gases, used chiefly as a reinforcing agent in the manufacture of bricks, concrete, etc.
Origin of fly ash
First recorded in 1930–35
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- fine solid particles of ash carried into the air during combustion, esp the combustion of pulverized fuel in power stations