rumble seat

plural rumble seats

1. datedAn extra passenger seat or row of seats in a carriage or automobile, typically folding away into a rear storage compartment.

   Vito does a lot of his own felting, dealing direct with Indians who are apt to show up here at all hours with a rumble seat full of beaver hides […].

   2025, Thomas Pynchon, Shadow Ticket, Jonathan Cape, page 99

   1 more example

   I suspected I wouldn't care an awful lot for his companionship, so I put him and another one in the rumble seat, and with the other two in with me I found the trail back to the Parkway and turned south.

   1934, Rex Stout, Fer-de-Lance, Bantam, published 1992, →ISBN, pages 166–167

   Synonyms: rumble-tumble

2. colloquialaeronauticsA jump seat.