[f. COUPLE v. + -ER.]
1. One who couples; spec. one whose business it is to couple railway carriages or trucks.
1552. Huloet, Coupler, copulator.
1748. Smollett, Rod. Rand., xi. (1804), 58. No such creature as you neither—no ten pound sneaker—no quality coupler.
1774. Pennant, Tour Scot. in 1772 (1790), II. 95. Those infamous couplers despise the fulminations of the Kirk.
1885. Manch. Exam., 15 May, 5/7. Couplers [of railway carriages or trucks] … expose themselves to danger in shunting operations.
2. A thing that couples or links together. spec. a. In an organ: A contrivance for connecting two manuals, or a manual with the pedals, or two keys an octave apart on the same keyboard, so that both can be played by a single motion.
1668. Culpepper & Cole, Barthol. Anat., III. viii. 144/2. The Orbicular Muscles only moves the upper Eye-lid, and doth but embrace the lower, and knit it as a coupler.
1840. Penny Cycl., XVI. 492/1. These several parts, or organs, when brought together by stops, called couplers, give to the keys of the great organ the command of every pipe in the instrument.
1871. Pall Mall Gaz., 29 March, 8. It [the organ] is fitted with 125 stops and 32 couplers.
b. (See quot.) Also = COUPLING.
1874. Knight, Dict. Mech., Coupler … 2. The ring which slips upon the handles of a crucible tongs, or a nipping-tool of any kind. Also called reins.
