Terminology

Plural

A state where there are multiple conscious creature in a single brain

System

Used to refer to all the inhabitants of a brain, referred to as "system members"

Headmate

Also used to refer to a system member, an inhabitant of a brain

Front

As a noun: Represents the physical body
As a verb: A state where a system member can control the body

Switch

When the fronting member changes

Blurring

When multiple system members merge temporarily; may be confusing

Proxying

When a system member (usually the one who fronts) relays words/actions for another member

Headspace

A location that is mentally accessible by the system; this is usually where system members live when they are not fronting

Fictive

A system member who arrives in the system with the form, personality, and possibly memories of a fictional character. This does not mean the system member is any less real.

Little

A system member who, while being able to use a brain entirely, thinks and acts younger than the body is

Caretaker

A system member who watches over a little when they are fronting to ensure they are not putting the body or the system at risk

Travelling

When a system member temporarily changes the system they are in, for one reason or another

Shared memory

A system member's ability to share memories with the rest of the system or not, doesn't affect their ability to communicate with the rest of the system

Subsystem

A group of headmates inside a system, generally grouped because of a common characteristic