From Longman Business Dictionaryrack rentˈrack rent [countable]LAWPROPERTY an amount of money for renting a house, office etc that is not fixed or controlled by law, but is agreed between the person owning the property and the person renting it. In the US, this expression is used to talk about unfairly high rent charged for a propertyThe property was sub-let to tenants at rack rents. → rent