V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ARPANET
       Advanced Research Projects Agency NETwork (USA, network)


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

Advanced Research Projects Agency Network
ARPANET

    (ARPANET) A pioneering longhaul wide area
   network funded by DARPA (when it was still called "ARPA"?).
   It became operational in 1968 and served as the basis for
   early networking research, as well as a central backbone
   during the development of the Internet.  The ARPANET
   consisted of individual packet switching computers
   interconnected by leased lines.  Protocols used include
   FTP and telnet.  It has now been replaced by NSFnet.

   [1968 or 1969?]

   (1994-11-17)