- "horse with brown and white patches," 1650s, from skued "skewbald" (mid-15c.), of unknown origin, + bald "having white patches" (see bald). First element apparently unconnected with skew (v.); OED suggests 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."
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]