What is "jump joint"

Jump \Jump\, n.

1. The act of jumping; a leap; a spring; a bound. ``To advance by jumps.''
   --Locke.

2. An effort; an attempt; a venture. [Obs.]

   Our fortune lies Upon thisjump.
   --Shak.

3. The space traversed by a leap.

4. (Mining) A dislocation in a stratum; a fault.

5. (Arch.) An abrupt interruption of level in a piece of brickwork or masonry.

6. A jump-start; as, to get a jump from a passing mmotorist. From the jump, from the start or beginning. [Colloq.] Jump joint.

   1. A butt joint.

   2. A flush joint, as of plank in carvel-built vessels. Jump seat.

      1. A movable carriage seat.

      2. A carriage constructed with a seat which may be shifted so as to make room for second or extra seat. Also used adjectively; as, a jump-seat wagon.