"a split, crack," 1530s, with parasitic -k + Middle English chine (and replacing this word) "fissure, narrow valley," from Old English cinu, cine "fissure," related to cinan "to crack, split, gape," common Germanic (cf. Old Saxon and Old High German kinan, Gothic uskeinan, German keimen "to germinate;" Middle Dutch kene, Old Saxon kin, German Keim "germ;" ), from PIE root *geie- "to sprout, split open." The connection being in the notion of bursting open.