The term "marginal dollar" refers to an additional or incremental revenue earned from selling one more unit, attracting one extra customer, or generating an added penny in profit. It is often used in business and economics to describe the value of the last or final dollar that a company earns when it operates at full capacity or reaches its maximum potential. The concept suggests that each additional sale or revenue stream adds value to the overall financial performance of a company, but only up to a certain point where further increases in production or sales may not be worth the cost due to factors such as increased overhead expenses or diminishing returns.