A hypothetical substance once believed to be present in all combustible materials and to be released during burning.

Roget 382: heat, caloric; temperature, warmth, fervor, calidity^†; incalescence^†, incandescence; glow, flush; fever, hectic.    phlogiston; fire, spark, scintillation, flash, flame, blaze; bonfire; firework, pyrotechnics, pyrotechny^†; wildfire; sheet of fire, lambent flame; devouring element; adiathermancy^†; recalescence [Phys.].    summer, dog days; canicular days^†; baking etc. 384; heat, white heat, tropical heat, Afric heat^†, Bengal heat^†, summer heat, blood heat; sirocco, simoom; broiling sun; insolation; warming etc. 384.    sun etc. (luminary) 423.    [Science of heat] pyrology^†; thermology^†, thermotics^†, thermodynamics; thermometer etc. 389.    [thermal units] calorie, gram-calorie, small calorie; kilocalorie, kilogram calorie, large calorie; British Thermal Unit, B.   T.U.; therm, quad.    [units of temperature] degrees Kelvin, kelvins, degrees centigrade, degrees Celsius; degrees Fahrenheit.    ... show more

Dutch: phlogiston
Polish: flogiston