What *is* a Horcrux

[redmorning]

No: HPFGUIDX 133450

JKR obviously invented this word.  From whence does it come?  What does 
it mean?

Hor--

mountain. (1.) One of the mountains of the chain of Seir or Edom, on the 
confines of Idumea (Num. 20:22-29; 33:37). It was one of the stations of 
the Israelites in the wilderness (33:37), which they reached in the 
circuitous route they were obliged to take because the Edomites refused 
them a passage through their territory. It was during the encampment 
here that Aaron died (Num. 33:37-41). (See AARON.) The Israelites passed 
this mountain several times in their wanderings. It bears the modern 
name of Jebel Harun, and is the highest and most conspicious

or

*hor* [From Latin 'hora', extant in Hindi, Romance (Spanish, Italian, 
French), English ('hour'), auxiliaries (Esperanto, Novial).] hour -- a 
time period of 60 minutes

Something else?

***

Crux (or Crux Australis) is the scientific name of the Southern Cross 
constellation. This well-known, cross-shaped Southern Hemisphere 
constellation is on the Australian flag. The brightest star in Crux is 
Acrux (alpha Cru), a double-star system at the base of the cross. The 
second-brightest star is Becrux or Mimosa (Beta Cru); the 
third-brightest is Gacrux (Gamma Cru). The Jewel Box (also known as 
Kappa Crucis) is an open cluster of about 100 stars in the Southern 
Cross. Crux lies on the Milky Way and is surrounded by the constellation 
Centaurus on three sides.

or
crux Pronunciation <javascript:play('C0779000')> (krks, krks)
/n./ /pl./ *cruxes* or *cruces* (krsz)
*1. * The basic, central, or critical point or feature: the crux of the 
matter; the crux of an argument.
*2. * A puzzling or apparently insoluble problem.

or

Probably short for Medieval Latin crux (interpretum), /torment (of 
interpreters)/, from Latin crux, /cross/.]

Just wondering what we're looking for.

Jemima