Source : WordNet®

minicomputer
     n : a digital computer of medium size

Source : Free On-Line Dictionary of Computing

minicomputer
     
         A computer built between about 1963 and 1987,
        smaller and less powerful than a {mainframe}, typically about
        the size and shape of a wardrobe, mounted in a single tall
        rack.
     
        Minicomputers were characterised by short {word} lengths of 8
        to 32 {bit}s, limited hardware and software facilities and
        small physical size.  Their low cost made them suitable for a
        wide variety of applications such as industrial control, where
        a small, dedicated computer which is permanently assigned to
        one application, is needed. In recent years, improvements in
        device technology have resulted in minicomputers which are
        comparable in performance to large {second generation
        computers} and greatly exceed the performance of {first
        generation} {computers}.
     
        The processor was typically built using low integration logic
        {integrated circuits} - {TTL} or maybe {ECL}, thus
        distinguishing it from a {microcomputer} which is built around
        a {microprocessor} - a processor on a single (or maybe a few)
        ICs.
     
        {DEC}'s {PDP-1} was the first minicomputer and their {PDP-11}
        was the most successful, closely followed (in both time and
        success) by the {VAX} (which {DEC} called a "{super
        minicomputer}").
     
        Another early minicomputer was the {LINC} developed at {MIT} in
        1963.
     
        Other minicomputers were the {AS/400}, the {PRIME} series, the
        {AP-3}, {Olivetti}'s {Audit 7} and the {Interdata 8/32}.
     
        [Others?]