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According to "Unfinished Tales", Dol Guldur was originally known in Tolkien's fictional language of Sindarin as "Amon Lanc" ("naked hill", from "amon" "hill" and "lanc" "bare" or "naked"). After Sauron came to reside there, it became known instead as "Dol Guldur" "Hill of Sorcery", acquiring a connotation of corruption and evil. The word "dol" strictly means "head" in elvish, but is applied to hills or mountains, as in "Dol Amroth". The word "guldur" signifies "black magic": "gûl" means "sorcery, magic", from the stem "ngol" or "nólë" meaning "long study, lore, knowledge"; and "dûr" means "dark".