the decomposition of a material, as coal, wood, etc., by heat in the absence of air, followed by the recovery of volatile products of the decomposition by condensation or other means: a type of calcination
See destructive distillation in American Heritage Dictionary 4
noun
A process by which organic substances such as wood, coal, and oil shale are decomposed by heat in the absence of air and distilled to produce useful products such as coke, charcoal, oils, and gases.