| Addon | A content source implementing this spec - either an HTTP server or a compiled module. |
| Host | The application that installs and calls addons (player, reader, browser, etc.). |
| Manifest | The manifest.json describing an addon's identity and capabilities. |
| Open Addon | An addon with no authentication requirement. Anyone with the URL can use it. |
| Locked Addon | An addon that requires a token/key to be used. Distributed as a tokenized URL and/or a compiled module. |
| Compiled Module | A single-file, portable script implementing the Addonium module contract (§9), optionally encrypted/obfuscated, unlocked with a key. |
| Base URL | The root URL a host uses to reach an HTTP addon, which may itself embed a token segment. |
| Client | A specific host application, build, or installation attempting to use an addon. Identified by a clientId it presents. |
| Allowlist | An optional, author-controlled list of clientIds permitted to use a Locked Addon. |