Term	Acronym	Vocabulary	Vocabulary Type	Preferred Term	Definitions	
Coal Fly Ash		Comprehensive Procurement Guideline Program Glossary 	Glossary and Key Word List		Definition: A by-product of coal burning at electricity plants. It is called "fly" ash because it is transported from the combustion chamber by exhaust gases.
	
Fly Ash		RCRA Orientation Manual 2008 Glossary 	Glossary and Key Word List		Definition: Particles of ash, such as particulate matter which may also have metals attached to them, that are carried up the stack of a combustion unit with gases during combustion.
	
Fly Ash		Terms of Environment 	Glossary and Key Word List		Definition: Non-combustible residual particles expelled by flue gas.
	
Fly Ash		RCRA Glossary of Terms 	Glossary and Key Word List		Definition: Non-combustible residual particles expelled by flue gas.
	
Fly Ash		EPA EV-Environmental Events-Waste 	Taxonomy		Definition 1: Particles of ash, such as particulate matter which may also have metals attached to them, that are carried up the stack of a combustion unit with gases during combustion. [RCRA Orientation Manual 2008 Glossary]
Definition 2: Non-combustible residual particles expelled by flue gas. [Terms of Environment]
Definition 3: The finely divided residue resulting from the combustion of ground or powdered coal and which is transported from the firebox through the boiler by flue gases; known in the United Kingdom as pulverized fuel ash (pfa). [FEMA Federal Guidelines for Dam Safety: Glossary of Terms]
Definition 4: Suspended particles, charred paper, dust, soot, and other partially oxidized matter carried in the products of combustion. [40 CFR 240.101 (CFR 2013)]
Definition 5: Ash that is carried out of the furnace by the gas stream and collected by mechanical precipitators, electrostatic precipitators, and/or fabric filters. Economizer ash is included when it is collected with fly ash. [40 CFR 423.11 (CFR 2013)]
Definition 6: Ash that is carried out of the furnace by a gas stream and collected by a capture device such as a mechanical precipitator, electrostatic precipitator, or fabric filter. Economizer ash is included in this definition when it is collected with fly ash. Ash is not included in this definition when it is collected in wet scrubber air pollution control systems whose primary purpose is particulate removal. [40 CFR 423.11 (CFR 2016)]
	
Residual Oil Fly Ash		EPA EV-Environmental Events-Waste 	Taxonomy		Definition: The inorganic residue remaining after the incomplete oxidation of oil and residual fuel oil.