1540s, alteration of Middle English garce "a gash, cut, wound, incision" (early 13c.), from Old North French garser "to scarify, cut, slash" (Old French *garse), apparently from Vulgar Latin *charassare, from Greek kharassein "engrave, sharpen, carve, cut," from PIE *gher- (4) "to scrape, scratch" (see character). Loss of -r- is characteristic (see ass (n.2)). Slang use for "vulva" dates to mid-1700s. Provincial English has a set of words (gashly, gashful, etc.) with forms from gash but senses from gast- "dreadful, frightful."