Mysteries of vernacular:

Jade,

a hard, typically green stone.

Until relatively recently,

gemstones were believed

to have magical, medicinal properties,

and nothing was more effective

at treating a kidney disorder than jade.

In the 16th century,

the Spanish returned from the New World

with the mineral in their cargo holds

and christened it, "piedra de la ijada,"

or loin stone.

It quickly became popular throughout Europe,

both as a cure for internal ailments

and as a decorative ornament

and was renamed jade by the French,

a word that was borrowed by the English

and remains in use to this day.

In the 19th century,

French mineralogists discovered

that jade was being used

to describe two distinct minerals:

jadeite, which takes its name from jade,

and the more common nephrite,

the root of which is the Greek word nephros,

meaning kidney.

In addition to describing these two minerals,

jade also has an English homonym.

With roots that predate the popularity

of the lustral gemstone,

jade was used to refer to

either a disreputable woman

or a broken-down horse.

Thus, the word jaded, meaning worn out

or lacking any enthusiasm,

has nothing to do with the gemstone,

and instead, comes from the archaic,

equine-related definition.