ˌback ˈseat BrE AmE noun
1 . [countable] a seat at the back of a car, behind where the driver sits
2 . back seat driver informal
a) a passenger in the back of a car who gives unwanted advice to the driver about how to drive
b) someone in business or politics who tries to control things that they are not really responsible for
3 . take a back seat to accept a less important position than someone or something else:
Finally, Bryant decided to take a back seat and let his son run the company.