1. (Norse mythology) the primeval giant slain by Odin and his brothers and from whose body they created the world: the sea from his blood; the earth from his flesh; the mountains from his bones; the sky from his skull;
WordNet (r) 3.0 (2006):
Ymir
n 1: (Norse mythology) the primeval giant slain by Odin and his
brothers and from whose body they created the world: the
sea from his blood; the earth from his flesh; the mountains
from his bones; the sky from his skull