Marginal cost refers to the additional cost that a company incurs when producing one more unit of a product. This cost includes the cost of materials, labor, and overheads necessary to produce the one additional unit. Some synonyms for marginal cost include incremental cost, differential cost, and variable cost. Incremental cost refers to the cost incurred as a result of producing or selling an additional unit. Differential cost, on the other hand, compares and analyzes the difference in costs between two options or alternatives. Lastly, variable cost refers to the cost that varies with the level of production. All these synonyms are useful to understand the cost incurred by a company when increasing its production output.