Mainframes are ultra-high-performance computers made for high-volume, processor-intensive computing. They are typically used by large businesses and for scientific purposes. In the hierarchy of computers, mainframes are right below supercomputers, the most powerful computers in the world. (I think that's why they call them supercomputers.) However, a mainframe can usually execute many programs simultaneously at a high speed, whereas supercomputers are designed for single processes. Currently, the largest manufacturers of mainframes are IBM and Unisys.
MAINFRAME
Meaning of MAINFRAME in English
English glossary of computer and Internet terms. Английский глоссарий компьютерных и Интернет терминов. 2012