(1) A special-purpose buffer storage, smaller and faster than main storage, used to hold a copy of instructions and data obtained from main storage and likely to be needed next by the processor.
(2) A buffer that contains frequently accessed instructions and data; it is used to reduce access time.
(3) Memory used to improve access times to instructions, data, or both. Data that resides in cache memory is normally a copy of data that resides elsewhere in slower, less expensive storage, such as on a disk or on another network node.
(4) To place, hide, or store frequently used information locally for quick retrieval.