• irl: Terms historically referencing the relationship between individuals with total authority and those without any.
• tech: In technology, a relationship in which one device (the "master") controls one or more other devices (the "slaves").
• also see: Thread, Daemon

(Note: The terms "master" and "slave" have been discouraged due to their historical context and sensitivity. Alternatives like "primary" and "secondary" or "main" and "replica" are used in many settings.)