The Free On-line Dictionary of Computing (30 December 2018):

data bus

    The bus (connections between and within the
   CPU, memory, and peripherals) used to carry data.  Other
   connections are the address bus and control signals.

   The width and clock rate of the data bus determine its data
   rate (the number of bytes per second it can carry), which is
   one of the main factors determining the processing power of a
   computer.  Most current processor designs use a 32-bit bus,
   meaning that 32 bits of data can be transferred at once.  Some
   processors have an internal data bus which is wider than their
   external bus in order to make external connections cheaper
   while retaining some of the benefits in processing power of a
   wider bus.

   See also data path.

   (1995-01-16)