split-level (adj.)

1640s, past-participle adjective from split (v.). Split decision is from 1946 of court rulings, 1951 in boxing. Split shift is from 1904. Split personality first attested 1899.

mid-14c., "tool to indicate a horizontal line," from Old French livel "a level" (13c.), ultimately from Latin libella "a balance, level" (also a monetary unit), diminutive of libra "balance, scale, unit of weight" (see Libra). Spanish nivel, Modern French niveau are from the same source but altered by dissimilation.

Meaning "position as marked by a horizontal line" (as in sea-level) is from 1530s; meaning "flat surface" is from 1630s; meaning "level tract of land" is from 1620s. Figurative meaning in reference to social, moral, or intellectual condition is from c. 1600. Figurative phrase on the level "fair, honest" is from 1872; earlier it meant "moderate, without great ambition" (1790).