What is "joint coupling"

Joint \Joint\ (joint), n. [F. joint, fr. joindre, p. p. joint. See Join.]

1. The place or part where two things or parts are joined or united; the union of two or more smooth or even surfaces admitting of a close-fitting or junction; junction; as, a joint between two pieces of timber; a joint in a pipe.

2. A joining of two things or parts so as to admit of motion; an articulation, whether movable or not; a hinge; as, the knee joint; a node or joint of a stem; a ball and socket joint. See Articulation.

   A scaly gauntlet now, with joints of steel, Must glove this hand.
   --Shak.

   To tear thee joint by joint.
   --Milton.

3. The part or space included between two joints, knots, nodes, or articulations; as, a joint of cane or of a grass stem; a joint of the leg.

4. Any one of the large pieces of meat, as cut into portions by the butcher for roasting.

5. (Geol.) A plane of fracture, or divisional plane, of a rock transverse to the stratification.

6. (Arch.) The space between the adjacent surfaces of two bodies joined and held together, as by means of cement, mortar, etc.; as, a thin joint.

7. The means whereby the meeting surfaces of pieces in a structure are secured together.

8. [ Jag a notch.] A projecting or retreating part in something; any irregularity of line or surface, as in a wall. [Now Chiefly U. S.]

9. (Theaters) A narrow piece of scenery used to join together two flats or wings of an interior setting.

10. a disreputable establishment, or a place of low resort, as for smoking opium; -- also used for a commercial establishment, implying a less than impeccable reputation, but often in jest; as, talking about a high-class joint is an oxymoron. [Slang]

11. a marijuana cigarette. [Slang]

12. prison; -- used with ``the''. [Slang] `` he spent five years in the joint.'' Coursing joint (Masonry), the mortar joint between two courses of bricks or stones. Fish joint, Miter joint, Universal joint, etc. See under Fish, Miter, etc. Joint bolt, a bolt for fastening two pieces, as of wood, one endwise to the other, having a nut embedded in one of the pieces. Joint chair (Railroad), the chair that supports the ends of abutting rails. Joint coupling, a universal joint for coupling shafting. See under Universal. Joint hinge, a hinge having long leaves; a strap hinge. Joint splice, a re["e]nforce at a joint, to sustain the parts in their true relation. Joint stool.

    1. A stool consisting of jointed parts; a folding stool.
       --Shak.

    2. A block for supporting the end of a piece at a joint; a joint chair.

       Out of joint, out of place; dislocated, as when the head of a bone slips from its socket; hence, not working well together; disordered. ``The time is out of joint.''
       --Shak.