A high-level computer designed for intensive computational tasks and used by large corporations. Mainframes are often shared by multiple users connected to the computer via terminals. Originally refers to the cabinet containing the CPU of a room-sized batch-processing machine.An ultra-high-performance computer made for high-volume, processor-intensive computing. They are typically used by large businesses and for scientific purposes. A high-capacity, fast central computer used by large organisations to store vast amounts of data and commercial transactions, and to handle and coordinate hundreds or thousands of terminals and simple PCs. Usually requires professionals to run it.