Tolkien invented neither orcs, nor the term "orc". The word "orc", related to the term "orkney", is from Beowulf "Þanon untydras ealle onwocon,/eotenas ond ylfe, ond orcneas ." "The concept of a generally despicable, probably inherently evil race of foot soldiers," 1 probably extends back to antiquity. More @Wikipedia
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