Periphery vs Peripheral

This is a concrete example of the project naming ontology in action.

The rule

Form	Grammatical Role	Meaning	When to Use
Periphery	Noun	The entire external system or domain — the collection of all peripherals.	When the component is the domain itself.
Peripheral	Adjective	Describing something that belongs to or relates to the Periphery.	When the component is a thing within or from the domain.

This mirrors the anatomical pattern already established:

Noun (Structure)	Adjective Form	Example
Thalamus	Thalamic	ThalamicTerminal
Cortex	Cortical	CorticalTerminal
Cerebrum	Cerebral	CerebralTerminal
Periphery	Peripheral	PeripheralTerminal

Applied vocabulary

Component	Name	Why
The relay that manages the Periphery	PeripheryRelay	It is the relay of the Periphery domain.
The cortex that bridges the Periphery	PeripheryCortex	It is the cortex of the Periphery domain.
The registry of all peripherals	PeripheryRegistry	It is the registry of the Periphery domain.
The terminal for the Periphery	PeripheralTerminal	It is a terminal belonging to the Periphery.
A signal from the Periphery	PeripheralSignal	It is a signal from the Periphery.
A message from the Periphery	PeripheralMessage	It is a message from the Periphery.
A plug-in unit	Peripheral	It is a unit belonging to the Periphery.

Simple heuristic

Ask yourself: “Is this component the domain itself, or is it a thing that belongs to the domain?”

• The domain itself → use Periphery (noun).
• A thing belonging to the domain → use Peripheral (adjective).

Visual model

┌─────────────────────────────────────────────────────────────────────┐
│                       Periphery (Noun)                             │
│  ┌───────────────────────────────────────────────────────────────┐│
│  │  PeripheryRelay                                              ││
│  │  PeripheryCortex                                             ││
│  │  PeripheryRegistry                                           ││
│  └───────────────────────────────────────────────────────────────┘│
│                              │                                      │
│                              │ Contains / Produces                 │
│                              ▼                                      │
│  ┌───────────────────────────────────────────────────────────────┐│
│  │                   Peripheral (Adjective)                      ││
│  │  ┌─────────────────────────────────────────────────────────┐  ││
│  │  │  PeripheralTerminal                                    │  ││
│  │  │  PeripheralSignal                                      │  ││
│  │  │  PeripheralMessage                                     │  ││
│  │  │  Peripheral (the plug-in unit)                         │  ││
│  │  └─────────────────────────────────────────────────────────┘  ││
│  └───────────────────────────────────────────────────────────────┘│
└─────────────────────────────────────────────────────────────────────┘

Summary

Question	Answer
Periphery or Peripheral?	Both — each has a distinct grammatical role.
When to use Periphery?	When the component is the domain (the collection, the system).
When to use Peripheral?	When the component belongs to or comes from the domain.
What is the pattern?	Noun for the domain, adjective for things within it — same as Thalamus → Thalamic, Cortex → Cortical.

Canonical rule

When naming something in the project, always decide whether it is the domain itself or an element belonging to that domain. If it is the domain, use Periphery; if it is the belonging thing, use Peripheral.