ornamental stone, 1721, earlier iada (1590s), from French le jade, misdivision of earlier l'ejade, from Spanish piedra de (la) ijada or yjada (1560s), "(stone of) colic or pain in the side" (jade was thought to cure this), from Vulgar Latin *iliata, from Latin ileus "severe colic" (see ileus). As an adjective from 1865.
"worn-out horse," late 14c., apparently originally "cart horse," a word of uncertain origin. Barnhart and Century Dictionary suggests a variant of yaid, yald "whore," literally "mare" (c. 1400), from a Scandinavian source akin to Old Norse jalda "mare," and ultimately from Finno-Ugric (compare Mordvin al'd'a "mare"). But OED finds the assumption of a Scandinavian connection "without reason." As a term of abuse for a woman, it dates from 1550s; in early use also of mean or worthless men, and sometimes simply "a young woman."