Source : Free On-Line Dictionary of Computing

Nibble Mode DRAM
     
         A standard {DRAM} where four successive {bits} can
        be clocked out of the single data line by successive pulses on
        the CAS\ line while RAS\ is active.  A column address is only
        required for the first bit.
     
        This mode is now unfashionable but can be found on some older
        64 kilobit and 256 kilobit chips.
     
        (1997-12-03)