eldritch (adj.)youdaoicibaDictYouDict[eldritch 词源字典]
"hideous, ghastly, weird," c. 1500, of uncertain origin; apparently somehow from elf (compare Scottish variant elphrish), an explanation OED finds "suitable;" Watkins connects its elements with Old English el- "else, otherwise" and rice "realm."[eldritch etymology, eldritch origin, 英语词源]