What is "right and left coupling"

Right \Right\ (r[imac]t), a. [OE. right, riht, AS. riht; akin to D. regt, OS. & OHG. reht, G. recht, Dan. ret, Sw. r["a]tt, Icel. r["e]ttr, Goth. ra['i]hts, L. rectus, p. p. of regere to guide, rule; cf. Skr. [.r]ju straight, right. [root]115. Cf. Adroit, Alert, Correct, Dress, Regular, Rector, Recto, Rectum, Regent, Region, Realm, Rich, Royal, Rule.]

1. Straight; direct; not crooked; as, a right line. ``Right as any line.''
   --Chaucer

2. Upright; erect from a base; having an upright axis; not oblique; as, right ascension; a right pyramid or cone.

3. Conformed to the constitution of man and the will of God, or to justice and equity; not deviating from the true and just; according with truth and duty; just; true. That which is conformable to the Supreme Rule is absolutely right, and is called right simply without relation to a special end. --Whately. 2. Fit; suitable; proper; correct; becoming; as, the right man in the right place; the right way from London to Oxford. 5. Characterized by reality or genuineness; real; actual; not spurious. ``His right wife.'' --Chaucer. In this battle, . . . the Britons never more plainly manifested themselves to be right barbarians. --Milton. 6. According with truth; passing a true judgment; conforming to fact or intent; not mistaken or wrong; not erroneous; correct; as, this is the right faith. You are right, Justice, and you weigh this well. --Shak. If there be no prospect beyond the grave, the inference is . . . right, ``Let us eat and drink, for to-morrow we die.'' --Locke. 7. Most favorable or convenient; fortunate. The lady has been disappointed on the right side. --Spectator. 8. Of or pertaining to that side of the body in man on which the muscular action is usually stronger than on the other side; -- opposed to left when used in reference to a part of the body; as, the right side, hand, arm. Also applied to the corresponding side of the lower animals. Became the sovereign's favorite, his right hand. --Longfellow. Note: In designating the banks of a river, right and left are used always with reference to the position of one who is facing in the direction of the current's flow. 9. Well placed, disposed, or adjusted; orderly; well regulated; correctly done. 10. Designed to be placed or worn outward; as, the right side of a piece of cloth. At right angles, so as to form a right angle or right angles, as when one line crosses another perpendicularly. Right and left, in both or all directions. [Colloq.] Right and left coupling (Pipe fitting), a coupling the opposite ends of which are tapped for a right-handed screw and a left-handed screw, respectivelly. Right angle.

   1. The angle formed by one line meeting another perpendicularly, as the angles ABD, DBC.

   2. (Spherics) A spherical angle included between the axes of two great circles whose planes are perpendicular to each other.

      Right ascension. See under Ascension.

      Right Center (Politics), those members belonging to the Center in a legislative assembly who have sympathies with the Right on political questions. See Center, n., 5.

      Right cone, Right cylinder, Right prism, Right pyramid (Geom.), a cone, cylinder, prism, or pyramid, the axis of which is perpendicular to the base.

      Right line. See under Line.

      Right sailing (Naut.), sailing on one of the four cardinal points, so as to alter a ship's latitude or its longitude, but not both.
      --Ham. Nav. Encyc.

      Right sphere (Astron. & Geol.), a sphere in such a position that the equator cuts the horizon at right angles; in spherical projections, that position of the sphere in which the primitive plane coincides with the plane of the equator.

      Note: Right is used elliptically for it is right, what you say is right, true.

      ``Right,'' cries his lordship.
      --Pope.

      Syn: Straight; direct; perpendicular; upright; lawful; rightful; true; correct; just; equitable; proper; suitable; becoming.