Final answer:
Indirect materials in manufacturing are materials that cannot be cost-effectively traced to finished goods, unlike direct materials which are easily traced and significant in cost.
Step-by-step explanation:
Materials that are used in manufacturing that cannot be cost-effectively traced to finished goods are called Indirect materials. These materials contribute to the production process but are not directly traceable to the end product due to either their insignificant cost in comparison to the total cost of the product or their indistinguishable nature when used across various products. For example, the glue used in furniture making or the lubricants and cleaning supplies in a machinery shop are considered indirect materials. They differ from direct materials, which are easily traced to the finished good, forming a significant part of the product's cost, like the wood for a table or the processor in a computer.