From The Free On-line Dictionary of Computing (30 December 2018) :
packet
data packet
The unit of data sent across a network. "Packet" is a
generic term used to describe a unit of data at any layer of
the OSI protocol stack, but it is most correctly used to
describe application layer data units ("{application
protocol data unit", APDU).
See also datagram, frame.
(1994-11-30)