c.1600, "beam or plank on which something rests," especially on which something heavy can be rolled from place to place (1782), of uncertain origin, probably from a Scandinavian source akin to Old Norse skið "stick of wood" (see ski (n.)). As "a sliding along" from 1890; specifically of motor vehicles from 1903. Skid-mark is from 1914.
In the timber regions of the American West, skids laid down one after another to form a road were "a poor thing for pleasure walks, but admirably adapted for hauling logs on the ground with a minimum of friction" ["Out West" magazine, October 1903]. A skid as something used to facilitate downhill motion led to figurative phrases such as hit the skids "go into rapid decline" (1909), and cf. skid row.
1670s, "apply a skid to (a wheel, to keep it from turning)," from skid (n.). Meaning "slide along" first recorded 1838; extended sense of "slip sideways" (on a wet road, etc.) first recorded 1884. The original notion is of a block of wood for stopping a wheel; the modern senses are from the notion of a wheel slipping when blocked from revolving.
On a failing or declining course; deteriorating: After that scandal his whole career was on the skids
[1921+; ultimately fr the skids, ''long pieces of timber,'' on which barrels, logs, and other heavy objects were rolled or slid, sometimes on a downgrade]
skell (1980s+ New York City police)