Defnintions

Nobilis uses a lot of specific terms, some, like Noble or Chancel, capitalised to indicate importance, and some italicised (like dementia animus) because they're in pidgin Latin.

Terms

Anchor:

An Anchor is a mortal who has been given a fragment of a Sovereign's power. This has the effect of binding the mortal to the Soveriegn. A Sovereign can only Anchor a mortal who he/she either loves or hates. Anchors are, by the nature of the connection, loyal to the Sovereign's Imperator's goals, though not necessarily to the Soverign themselves. Anchors can be used by Soveriegns to perform Miracles remotely, and as proxies. A Soveriegn can control his/her Anchor as lightly as telepathic communication, or as strongly as complete control over the Anchor's body.

Auctoritas:

The "spiritual force field" generated by a Soveriegn's spiritus dei that resists the Miracles of other Powers. It generally extends about five feet from the Soveriegn it protects.

Chancel:

A Chancel is a place where an Imperator has placed their physical body, allowing them to create Soveriegns to protext thier body and Estates. Basic a private world where normal rules may not apply.

Dementia Animus:

When a mortal is exposed to something that they can't explain in the context of the reality they know, they suffer from Dementia Animus. This means that their preceptions of the world shift to Mythic Reality, and that they respond to a different world than the one that the rest of humanity sees. Think Alice stuck in Wonderland.

Domina/Dominus:

An alternate title for a Power or a Sovereign

Estate:

An Estate is the piece of reality that a given Power is tied to. For example, Lord Whiffle might be the Power of Poultry.

Imperator:

A being made entirely of spiritus Dei, a purely divine creature whose existence is the cause for a set of Estates.

Miracle:

A miracle is the basic unit of "empowered" action in Nobilis; shooting a gun with inhuman accuracy, or calling down fire from the skies are both miracles.

Mythic Reality:

cf Prosaic Reality. The world exists in two layers; in the Mythic layer, cars run because there is a car spirit that can be talked to, argued with or killed. The sun really is a chariot pulled across the sky by flaming horses, and there's a tall man holding up the sky. Nearly everything has a spirit that can be talked to. The spirits of intelligent beings do not always respond the same way that thier Prosaic counterparts do.
Nobles are unique in their ability to switch between Prosaic and Mythic Reality at will. Some parts of Mythic Reality resemble the Undershadow that Merlin travelled through.

Noble:

A mortal who has been given a shard of spiritus Dei by an Imperator, and entrusted with an Estate. A Noble's duties include protecting and serving the needs of his/her/its Estate, and protecting his/her/its Imperator's physical body and the Chancel that surrounds it.

Power:

Another name for a Noble.

Prosaic Reality:

cf Mythic Reality. Prosaic Reality is the world as we know it more or less; science has discovered rational rules that the world follows, the laws of physics are obeyed, and inanimate objects stay that way. Prosaic Reality is like a wrapper around Mythic Reality; if someone kills a car spirit in Mythic Reality, in Prosaic Reality, the car will break down. In extreme cases, history will be changed, so that the car will have been having problems for some months, so it's breakdown is not entirely unexpected. Imperators, Nobles and Anchors are all able to pick up on such changes in time, but to mortals, what Prosaic Reality says is how things happened. Changes made by Imperators are reflected by Prosaic Reality as natural events; if the Unicorn stabbed the sun with her horn, the citiznes of Amber would experience an eclipse. This would have been fully predictable by Amber's stargazers. This is because Imperators function almost entirely in Mythic Reality. Nobles, however, act simultaneously in both worlds, so a Noble's attack on the sun would cause both worlds to go dark, and likely leave the city of Amber full of minds shattered by dementia animus. Nobles can switch between percieving either of the two versions of Reality at will.

Sovereign:

Another name for a Noble.

Spirit World:

The Spirit World is distinct and different from both Mythic and Prosaic Realities. The Spirit World is a place where neither time nor space make sense. This is the place where Imperators focus much of thier attention on matters beyond the ken of mere Nobles.

Spiritus Dei:

The "fundamental stuff of the world", the "first cause" of a thing. This is the divine force of Creation. When an Imperator gives a mortal a shard of her soul, she is infusing that mortal with spiritus Dei