Synonyms for Mainframe (same or very similar meaning)
WordNet sense 1 (a large digital computer serving 100-400 users and occupying a special air-conditioned room):
mainframe computer
WordNet sense 2 ((computer science) the part of a computer (a microprocessor chip) that does most of the data processing):
processor, C.P.U., CPU, central processing unit, central processor
From the ODE community, based on WordNet
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