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. 2019
British Dictionary definitions for fly ash
fine solid particles of ash carried into the air during combustion, esp the combustion of pulverized fuel in power stations
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012