dragon

English dragon comes from Middle English dragoun, borrowed from Old French dragon, from Latin dracō(n), from Ancient Greek δράκων (drákōn), meaning a huge serpent or python, likely from δέρκομαι (dérkomai), 'to see clearly.'

The word traveled from Greek into Latin, then Old French, then Middle English, narrowing from 'giant serpent' toward the fire-breathing creature of legend, and largely displaced the native Old English words wyrm and draca.

The same Latin source dracō gives English drake, dragoon, and the names Draco and Dracon, all distant cousins of dragon.