Mainframe computers (colloquially referred to as "big iron") are computers used primarily by large organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and transaction processing.
英英词典
main frame n.
a large digital computer serving 100-400 users and occupying a special air-conditioned room
synonymous: mainframe, mainframe computer
(computer science) the part of a computer (a microprocessor chip) that does most of the data processing
synonymous: central processing unit, CPU, C.P.U., central processor, processor, mainframe