main memory

from the GNU version of the Collaborative International Dictionary of English.

• noun (Computers) The memory in a computer that holds programs and data for rapid access during execution of a program; it usually hold the largest quantity of rapid-access storage in a computer; -- also called RAM (random access memory. It is contrasted to ROM, disk data storage, cache, registers and other forms of data storage.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun computing The primary volatile memory of a computer, not including memory cache nor persistent disk storage, nor external storage.