Lindworms are dragons in Norse and Germanic mythology. Their serpent-like features set them apart from other dragons. Their bodies are long and scaly and they usually do not have any limbs. They do have wings, though, giving them the capability to fly. Some of them are known to be capable of speech.
Nidhogg is a prime lindworm example. He is the dragon that gnaws at the roots of Yggdrasil and is responsible for taking care of the souls of oath breakers when they get to Helheim. Another example is Fafnir, who used to be a dwarf. He becomes a lindworm after he is cursed with greed.