Merriam-Webster Collegiate Dictionary - cerebrum

 noun  (plural -brums or cerebra)  Etymology: Latin  Date: 1615  1. brain 1a  2. an enlarged anterior or upper part of the brain; especially the expanded anterior portion of the brain that in higher mammals overlies the rest of the brain, consists of cerebral hemispheres and connecting structures, and is considered to be the seat of conscious mental processes ; telencephalon