A uhost is an “user” host, a SimulationHost process running in the ThereClient on a member’s computer. This is as opposed to an ihost (“internal” host), a SimulationHost process running on a server at MakenaTechnologies.
Alternative definition from a forum post:
The uhost (“you” host) is the client machine where the ThereClient runs. This is as opposed to an ihost (“I” host), a simulation server at MakenaTechnologies. “I” and “you” are therefore server-centric terms.