The word for dragon in Germanic mythology and its descendants is worm (Old English: wyrm, Old High German: wurm, Old Norse: ormr), meaning snake or serpent. In Old English wyrm means "serpent", draca means "dragon". Finnish lohikäärme means directly "salmon-snake", but the word lohi- was originally louhi- meaning crags or rocks, a "mountain snake".
O.E. wurm, variant of wyrm "serpent, dragon," also in later O.E. "earthworm," from P.Gmc. *wurmiz (cf. O.S., O.H.G., Ger. wurm, O.Fris., Du. worm, O.N. ormr, Goth. waurms "serpent, worm"), from PIE *wrmi-/*wrmo- "worm" (cf. Gk. rhomos, L. vermis "worm," O.Rus. vermie "insects," Lith. varmas "insect, gnat"), possibly from base *wer- "turn" (see versus). The ancient category of these was much more extensive than the modern, scientific, one and included serpents, scorpions, maggots, and the supposed causes of certain diseases. In Eng., the -o- was a scribal substitution to avoid confusion of -u- and -r- (as also in some, come, monk etc.). As an insult meaning "abject, miserable person" it dates from O.E. The verb meaning "to move like a worm" is recorded from 1610, in fig. senses (attested from 1627) suggesting patient, sinuous progress.