Neoverse is a brand used by Arm to describe the infrastructure side of their business. In other words, the Neoverse incorporates the technologies of the Arm ecosystem that spans from the edge to the cloud.
Arm introduced the 'Neoverse' at Arm TechCon 2018. It's a general term that may be used by both Arm and their partners who work on the Arm ecosystem as it pertains to infrastructure (e.g., routers, switching, servers). The term covers everything from the edge to the cloud and is not part of the client ecosystem which is covered by the Cortex brand.
As part of the Neoverse, Arm is releasing specific microarchitectures with higher performance and power targets for the server markets.