The action of accidentally leaving something behind on an airplane, most notably in the seatback storage area in front on you.
I was reading a great article in Wired, but I seatbacked it on the flight back from Kona.
by johntex December 08, 2004
When leaving a chair, you can say "I call seatback" and no one else in the room can take the seat away from you. Similar to saying, "I call shotgun" when approaching a car.
No way, you can't sit there, I called seatback!"
by Jamie Kozma March 11, 2006
Anouncing that you are reserving your seat when you getting up to get something.
Jason you dumbass,I'm getting a drink. Seat back.
by Jason you dumbass November 20, 2005