*gleubh-

"to split, part or divide by force," Old English cleofan, cleven, cliven "to split, separate" (class II strong verb, past tense cleaf, past participle clofen), from Proto-Germanic *kleuban (source also of Old Saxon klioban, Old Norse kljufa, Danish klöve, Dutch kloven, Old High German klioban, German klieben "to cleave, split"), from PIE root *gleubh- "to tear apart, cleave."

Past tense form clave is recorded in Northern writers from 14c. and was used with both verbs (see cleave (v.2)), apparently by analogy with other Middle English strong verbs. Clave was common to c. 1600 and still alive at the time of the KJV; weak past tense cleaved for this verb also emerged in 14c.; cleft is still later. The past participle cloven survives, though mostly in compounds.

1570s, alteration (by influence of cleft, new weak past participle of cleave (v.1)), of Middle English clift "fissure, rift, space or opening made by cleaving" (early 14c.), from Old English geclyft (adj.) "split, cloven," from Proto-Germanic *kluftis (compare Old High German chluft, German Kluft, Danish kløft "cleft, fissure, gap"), from PIE root *gleubh- "to tear apart, cleave." In Middle English anatomy, it meant "the parting of the thighs" (early 14c.).