Aether

In the Aether Story, the Aether refers to the fabric of reality itself. The term "Aether" can also refer to several things within the context of Call of Duty.
*Aether (song) - An easter-egg song in the Call of Duty: Black Ops II Zombies map Origins.
*Aetherium - An element that is central to the Dark Aether Story.
**Aetherium Crystals - Crystals of said element that are used to upgrade skills in Call of Duty: Black Ops Cold War Zombies.
*Aether Canister - An item in Black Ops Cold War, in Outbreak.
*Aether Reactor - A utility item in Firebase Z.
*Aetherscope - A craftable item in Die Maschine.
*Aether Shroud - A Field Upgrade in Black Ops Cold War and Call of Duty: Vanguard Zombies.
*Aether Tool - An object featured in Black Ops Cold War Zombies.
*Agartha - A realm referred to as the "Aether".
*Dark Aether - The Aether's opposite, also simply referred to as "the Aether" later on in the Dark Aether Story.
**Dark Aether Camouflage - A camouflage in Black Ops Cold War based off of the pseudonymous dimension.
*Element 115 - An element central to the Aether Story that is also referred to as Aether.
**Elemental Shard - A special piece of Element 115 in Call of Duty: Black Ops 4, referred to as the "Aether that Binds Them".
*Moon Pyramid Device - A device in the Aether Story also referred to as the Aether Pyramid.