early 13c., from O.Fr. dragon, from L. draconem (nom. draco) "huge serpent, dragon," from Gk. drakon (gen. drakontos) "serpent, giant seafish," apparently from drak-, strong aorist stem of derkesthai "to see clearly," from PIE *derk- "to see." Perhaps the lit. sense is "the one with the (deadly) glance."