cerebral cortex UK /ˈsɛ.ɹɪb.ɹəl ˈkɔːtɛks/US /səˈɹiː.bɹəl ˈkɔɹtɛks/ noun1 •The grey, folded, outermost layer of the cerebrum that is responsible for higher brain processes such as sensation, voluntary muscle movement, thought, reasoning, and memory. formscerebral cortexes · cerebral cortices