the verb-stem used in Comb.: jump-cord, a cord to be jumped over; jump-coupling, a coupling of which the box consists of a collar of metal bored to fit the two connected ends of the shafts = thimble-coupling; jump-joint, (a) a joint in which the parts are welded end to end together, a butt-joint (see BUTT sb.7 2); (b) a flush-joint in which the edges of the plates or planking are laid close together and make a smooth surface; hence jump-jointed a.; jump-ring, a wire ring made by bringing the two ends together without welding; jump-rocks, a catostomoid fish, Moxostoma cervinum, of southern U.S.; jump-seat, a movable carriage-seat; also adj. and sb. (ellipt.) (a carriage) provided with such a seat which can be brought into use when required; jump-stroke (Croquet): see quot.; jump-weld, a weld effected by hammering together the heated ends of two pieces of metal; a butt-weld; hence jump-weld v.
1874. Thearle, Naval Archit., 95. Among these early systems [of combining the bottom plates] was that of flush or *jump joints and butts connected by edge strips and butt straps on the inside surface.
1867. Smyth, Sailor’s Word-bk., *Jump-jointed, when the plates of an iron vessel are flush, as in those that are carvel-built.
1864. Webster, *Jump-seat, a carriage constructed with a movable seat;… a movable carriage-seat. Ibid., Jump-seat, a., having a movable seat; as, a jump-seat rock-away.
1875. Knight, Dict. Mech., Jump-seat,… a kind of open buggy which has a shifting seat or seats…. It may be arranged as a double or single seat vehicle.
1874. J. D. Heath, Croquet-Player, 41. The leapfrog or *jump stroke has lately been used … with great success, for getting through narrow hoops at a very oblique angle…. The effect of this stroke is to make the ball jump up when it strikes the further wire of the hoop.
1864. Webster, s.v. Weld, Butt-weld, or *jump-weld.
