What is the name of the magic realm between worlds in God of War (2018)?

The magic realm between worlds in God of War (2018) is called the Realm Between Realms.

Kratos and Atreus use this strange dimension as a transitional space when traveling through the branches of Yggdrasil, the World Tree. The area is not one of the main mythological realms such as Midgard, Alfheim, or Helheim. Instead, it functions as an inter-realm hub connected to the game's magical travel system.

The Realm Between Realms is reached through the travel room, where the pair can select destinations and activate the Bifröst. Its appearance is intentionally abstract, with dark space, floating pathways, and glowing structures rather than the landscapes associated with the individual realms.

Several terms are easy to mix up. Yggdrasil is the cosmic tree linking the realms, while the Bifröst is the travel mechanism or bridge of light. The Lake of Nine is a location in Midgard. None of those names is the formal name of the in-between dimension.