sb. U.S. [ad. Sp. cincha girth, cingle.] The saddle-girth used in Mexico, and the adjacent parts of the United States, usually made of separate twisted strands of horse-hair.

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1872.  C. King, Mountain. Sierra Nev., vi. 119. I leaned down and felt of the cinch, to see if it had slipped forward.

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1884.  Joaquin Miller, Memorie & Rime, 168. Colonel Bill had just set the rowels of his great Spanish spurs in the broad cinch in order to push his horse.

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  Hence Cinch v. to girth tightly; also fig. to ‘put the screw on.’

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1875.  S. Williams, in Scribner’s Mag., July, 277/1 (Hoppe). A man who is hurt in a mining transaction is ‘cinched’ [San Francisco localism].

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1884.  Joaquin Miller, Memorie & Rime, 56. The gray old Californian sinched his little mule till she grunted.

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1888.  Bryce, Amer. Commw., III. 239. To use an expressive Californian phrase, capital, and especially accumulated capital, wherever it was found, was to be ‘cinched.’

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