The word dragon derives from Greek δρακων, via Latin draco. It is attested in Middle English from the 13th century, in the context of medieval bestiaries and legends.

The Greek and Latin term referred to any great serpent, not necessarily mythological, and this usage was also current in English up to the 18th century. Today the great komodo lizard Varanus komodoensis is also known in English as the Komodo dragon. The King James Bible uses the words "serpent", "dragon" and "Devil" in a fairly interchangeable manner