Uncore
Beginner
The parts of a processor chip that are not the processor cores themselves, such as memory and connections to the outside.
Novice
The shared parts of a processor chip outside the cores: caches (small, fast on-chip memories), the on-chip connections, memory controllers and input/output. Adding cores does not add more of it.
Expert
Often treated as a fixed cost in early power and area models. The interface circuits (PHYs) are sized by the standard they implement, so they shrink little with each new manufacturing generation and can dominate a small chip.
Explained in Specification (Design Flow).