Definition of the term Coal Tar Pitch A bituminous material, which is a by-product from the coking of coal. It is used as the waterproofing material for tar and gravel built-up roofing. Related Posts Definition of the term Relative Heat Gain The amount of heat gain through a glass product taking… Definition of the term Rise In stairs, the vertical height of a step or flight… Definition of the term RPM Revolutions per Minute.