Wiktionary
n. (context fantasy English) A fictional monster that devours earthen and silicate materials and can move freely through earth.
Wikipedia
Xorn is a fictional character published by Marvel Comics. First appearing in New X-Men Annual 2001, Xorn was a new addition to the X-Men membership during writer Grant Morrison's revamp of the franchise.
Originally depicted as a Chinese mutant with a "star for a brain", he is eventually revealed to be the X-Men's nemesis Magneto in disguise at the climax of Morrison's run. After Magneto is apparently killed in the "Planet X" story arc, he appears alive and well a few months later in 2004's Excalibur (Vol. 3) #1, which established that Xorn never was Magneto. Marvel has presented several partial explanations, both in the comics pages and in the press as to the true nature, identity, and motives of Xorn.
In the Dungeons & Dragons fantasy role-playing game, xorn are outsiders from the Elemental Plane of Earth.
Usage examples of "xorn".
They tell of how they came here, cast out from the realm of the gods, to dwell upon the face of Xorn as mortals.