The term 'concave lint trap' refers to a type of lint trap that is designed with a concave shape. This shape allows the lint to be collected in the center of the trap, making it easier to clean and maintain. The term 'innie' is an abbreviation for 'inwardly curved, ' which describes the shape of the concave lint trap. This type of lint trap is commonly used in clothes dryers to prevent lint from clogging the machine.