cinch (n.)youdaoicibaDictYouDict[cinch 词源字典]
1859, American English, "saddle-girth," from Spanish cincha "girdle," from Latin cingulum "a girdle, a swordbelt," from cingere "to surround, encircle," from PIE root *kenk- (1) "to gird, encircle" (cognates: Sanskrit kankate "binds," kanci "girdle;" Lithuanian kinkau "to harness horses"). Replaced earlier surcingle. Sense of "an easy thing" is 1898, via notion of "a sure hold" (1888).[cinch etymology, cinch origin, 英语词源]
cinch (v.)youdaoicibaDictYouDict
1866, "to pull in," from cinch (n.). Figurative meaning "make certain" is from 1891, American English slang. Related: Cinched; cinching.