gamemaster means to run a roleplaying game; to act as a game master. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Etymology
From the noun game master.
verb
- To run a roleplaying game; to act as a game master.“A few weeks before Wesley had asked me to gamemaster a role-playing narrative, I had purchased the Forgotten Realms Campaign Set.”