noun
( -s )
: the action or process of removing impurities from a crude or impure material: as
a. of metals : subjection to high heat or other purification methods (as electrolysis or treatment with chemicals)
fire refining of copper
— compare parting
b. of glass : fining 1b
c. of sugar : processing in a series of steps ending with crystallization
d. of petroleum : fractional distillation usually followed by other processing (as cracking)