Indirect materials definition. Analyzing the definition of key terms often provides more insight about concepts. Undirect Materials can be defined as – Costs incurred for the benefit of more than one cost object. Indirect costs can be contrasted to direct costs, both terms applying to a manufacturing company. Direct costs are costs that can applies specifically to a job or process, costs including direct labor and direct materials. Indirect costs are costs that cannot be directly applied to a job or process and are generally included in overhead. These costs could include indirect labor, indirect wages, and costs to the factory like deprecation and maintenance.