1580s, from Middle Dutch splitten, from Proto-Germanic *spl(e)it- (cf. Danish and Frisian splitte, Old Frisian splita, German spleißen "to split"), from PIE *(s)plei- "to split, splice" (see flint).
Meaning "leave, depart" first recorded 1954, U.S. slang. Of couples, "to separate, divorce" from 1942. To split the difference is from 1715; to split (one's) ticket in the U.S. political sense is attested from 1842. Splitting image "exact likeness" is from 1880. Split screen is from 1953; split shift is from 1955; split personality first attested 1919. Split-level as a type of building plan is recorded from 1952. Split-second first attested 1884, in reference to a type of stopwatch with two second hands that could be stopped independently; adjectival meaning "occurring in a fraction of a second" is from 1946.