Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
Wiktionary
n. 1 Any of the seats in the rear of a vehicle. 2 (context informal English) A powerless position.
Wikipedia
"Back Seat (of My Jeep)" is a song by LL Cool J, released as a single on June 1, 1993, for Def Jam Recordings, taken from his fifth album 14 Shots to the Dome. It was produced and written by LL Cool J and QD III. The song samples a drum loop from The Detroit Emeralds 1973 song " You're Gettin' a Little Too Smart".
"Back Seat (Of My Jeep)" was the most successful single from the critical and commercially disappointing album; it made it to 42 on the Billboard Hot 100 and 24 on the Hot R&B/Hip-Hop songs. "Back Seat" was packed along with another single, " Pink Cookies In a Plastic Bag Getting Crushed by Buildings", which charted at a lower position (#96 Pop, #34 R&B).
The song was sampled in Monica's 1995 song " Don't Take It Personal (Just One of Dem Days)."
Usage examples of "back seat".
Jam his foot down hard and hope that the surge of power would throw her into the back seatbut that was too chancy.