(băk′sēt′)n.1. A passenger who constantly advises, corrects, or nags the driver of a motor vehicle.2. A person who persists in giving unsolicited advice.back′-seat′ dri′ving n.
back-seat driver
n1. a passenger in a car who offers unwanted advice to the driver2. a person who offers advice on or tries to direct matters that are not his or her concernIdiomsSeebackseat driver