The Old English word “orcneas” helped inspire Tolkien’s use of the word “orc.”
The term appears in a passage of Beowulf listing monstrous beings descended from Cain. Tolkien was an expert in Old English and recognized the literary value of its unusual vocabulary. His orcs are not direct copies of the creatures in Beowulf, but the older word contributed to the form and atmosphere of Tolkien’s conception.
Tolkien used several related forms during the development of his mythology, including “orc” and “Ork.” In The Lord of the Rings, orcs are servants of dark powers and are presented as corrupted or bred creatures rather than as a single simple species with one origin explained consistently in every draft.
The word is also often linked to Latin orcus, meaning the underworld or death. Tolkien’s own linguistic interests included both historical connections and invented language history, so the exact relationship among these forms is more complicated than a claim that he simply copied one word.