The term 'Taxi Clock' refers to a device that is used in taxis to measure the time and distance of a journey. The device is also known as a METER, which is a five-letter word that can be used to complete the crossword. Taxi clocks are typically installed in the dashboard of the taxi and are used to calculate the fare for the customer. They are usually connected to the vehicle's odometer and can be programmed to charge different rates depending on the time of day or night.