piebald adj.

"magpie," mid-13c. (late 12c. as a surname), from Old French pie (13c.), from Latin pica "magpie" (see magpie).

c. 1300, ballede, "wanting hair in some part where it naturally grows," of uncertain origin. Perhaps with Middle English -ede adjectival suffix, from Celtic bal "white patch, blaze" especially on the head of a horse or other animal (from PIE root *bhel- (1) "to shine, flash, gleam").

Compare, from the same root, Sanskrit bhalam "brightness, forehead," Greek phalos "white," Latin fulcia "coot" (so called for the white patch on its head), Albanian bale "forehead." But connection with ball (n.1), on notion of "smooth, round" also has been suggested, and if not formed from it it was early associated with it. Middle English Compendium says it probably was formed on the root of ball, and compares Old Danish bældet.

Sometimes figurative: "meager" (14c.), "without ornament" (16c.), "open, undisguised" (19c.). Of automobile tires with worn treads, by 1930. Bald eagle is attested by 1680s; so called for its white head.

also skew-bald, 1650s, "having white and brown (or some other color) patches, spotted in an irregular manner" (used especially of horses), from skued, skeued "skewbald, of mixed colors" (early 15c.) + bald "having white patches" (see bald).

The first element is said to be unconnected with skew (v.), but Klein's sources say it is and Middle English Compendium offers that as a possibility; OED suggests it is perhaps from Old French escu "shield," but also notes a close resemblance in form and sense with Icelandic skjottr, "the history of which is equally obscure." Watkins says it is Scandinavian and akin to Old Norse sky "cloud" on the resemblance of the markings to cloud cover.

When the white is mixed with black it is called 'pie-bald,' with bay the name of 'skew-bald' is given to it. ["Youatt's 'The Horse,' " 1866]

As a noun meaning "skewbald horse" or other animal from 1863.