And a bit of linguistic trivia to go along with the CCP trivia.
The old english word "wyrm" (or it's old high german spelling, wurm) is the name for dragons in older germanic mythologies (as opposed to the modern word "dragon" which is derived from the latin word "draco"). Wyrm meant both dragons, and snakelike. The modern word worm has it's regular zoological definition, but could also be a loose reference to anything with a long, slender body with no limbs, or short/stunted limbs...
So yeah, great wyrms are really just oversized mutant worms with a bad case of acid indigestion '> Um, don't say that to their faces though unless you got plenty of elemental protection and some dragon slaying gear handy.