Cereb is not a stand-alone word. However, we can assume you meant "cerebrum," the largest part of the brain, which controls our conscious thoughts and voluntary actions. Some synonyms for cerebrum include gray matter, cortex, and neocortex. Gray matter is often used to mean the outermost layer of the brain, while cortex is a general term for the cerebrum's outer layer. The neocortex is the part of the cortex that is responsible for higher-level thinking, language, and conscious processing. These synonyms can help expand vocabulary when discussing the brain and neuroscience.