mainframe

Noun

• (computer science) the part of a computer (a microprocessor chip) that does most of the data processing
  • the CPU and the memory form the central part of a computer to which the peripherals are attached
    

• a large digital computer serving 100-400 users and occupying a special air-conditioned room

Related words

• Synonyms: 
  central processing unit , CPU , C.P.U. , central processor , processor , mainframe computer