Tolkien
The humanoid, non-maritime race of orcs that exists in Middle-earth is the invention of J. R. R. Tolkien, albeit one which he stated in a letter was influenced by George MacDonald's The Princess and the Goblin. The word is usually capitalised in Tolkien's writing, but not necessarily in other works.
Within Tolkien's invented languages, the Elvish words for orc are derived from a root ruk referring to fear and horror, from which is derived an expanded form of the root uruk. A noun *uruku is produced from the extended root. This eventually turns into Quenya urco, plural urqui. A related word *urkō produces Sindarin orch, plural yrch. The Quenya words are said to be less specific in meaning than the Sindarin, meaning 'bogey'. For the specific creatures called yrch by the Sindar, the Quenya word orco, with plurals orcor and orqui, was created.
These orcs had similar names in the other languages of Middle-earth: in Orkish uruk (restricted to the larger soldier-orcs); in the language of the Drúedain gorgûn; in Khuzdul rukhs, plural rakhâs; and in the language of Rohan and in the Common Speech, orc.
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