The term residual dividend refers to a method of calculating dividends. A dividend is a payment made by a company to its shareholders. It is essentially a portion of the company's profits that is divided amongst the people who own stock in the company. A residual dividend policy is one where a company uses residual or leftover equity to fund dividend payments. Typically, this method of dividend payment creates volatility in the dividend payments that may be undesirable for some investors.
Taobiz explains Residual Dividend
Companies that use the residual dividend policy first use the cash flow to fullfill necessary capital expenditures and the remaining amount available is paid out to shareholders. Also, if the company is maintaining a certain target debt to equity capital structure, then the full amount of the capital expenditure will not be paid entirely by equity but also with part debt.