(verb) go back and forth; swing back and forth between two states or conditions
(verb) reverse (a direction, attitude, or course of action)
(verb) do something in turns
Definitions for Ymir
(noun) (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