Etymology
Advertisement
jackass (n.)

"male ass," 1727, from jack (n.) + ass (n.1). Contemptuous meaning "stupid person" is attested by 1784 (Ignatius Sancho). Related: Jackassism (1837, American English); jackassery (1833).

Related entries & more 
Advertisement
jack-rabbit (n.)
also jackrabbit, large prairie hare, 1863, American English, shortening of jackass-rabbit (1851; see jackass + rabbit (n.)); so called for its long ears. Proverbial for bursts of speed (up to 45 mph).
Related entries & more 
jack (n.)
late 14c., jakke "a mechanical device," from the masc. name Jack. The proper name was used in Middle English for "any common fellow," and thereafter extended to various appliances which do the work of common servants (1570s). Also used generically of male animals (1620s, see jackass, jackdaw, etc.).

As a portable contrivance for raising weight by force from below, 1703. As the name of a device for pulling off boots from 1670s. The jack in a pack of playing cards (1670s) is in German Bauer "peasant." Slang meaning "money" is by 1890 (in earlier slang it meant "a small coin"). Jack-towel, one sewn together at the ends round a roller, is from 1795. The jack of Union Jack is a nautical term for "small flag at the bow of a ship" (1630s) and perhaps is from the word's secondary sense of "smaller than normal size."
Related entries & more 
sagebrush (n.)

collective name for a type of dry, shrubby plant that grows over the vast dry plains of the western U.S., by 1846, from sage (n.1), to which it has no biological affinity, + brush (n.2). Said to be so called for resemblance of its appearance or odor.

Sage-brush is very fair fuel, but as a vegetable it is a distinguished failure. Nothing can abide the taste of it but the jackass and his illegitimate child, the mule. ["Mark Twain," "Roughing It"]
Related entries & more