Definition: a cost of materials or supplies used, or an aggregate of such costs. A material cost may be either a ‘direct material cost’ or an ‘indirect material cost’ depending on whether it is a direct cost or an indirect cost. An alternative form of the term is ‘materials cost’. material cost may be either a ‘direct material cost’ or an ‘indirect material cost’ depending on whether it is a direct cost or an indirect cost. An alternative form of the term is ‘materials cost’.