1570s, alteration (by influence of cleft, new weak past participle of cleave (v.1)), of Middle English clift (early 14c.), from Old English geclyft (adj.) "split, cloven," from Proto-Germanic *kluftis (cf. Old High German and German kluft, Danish kløft "cleft"), from PIE *gleubh- (see glyph). In Middle English anatomy, it meant "the parting of the thighs" (early 14c.).
late 14c., past participle adjective from cleave (v.1)). Cleft palate attested from 1828.
A split or fissure between two parts.