WordNet (r) 3.0 (2006):

AARP
    n 1: an association of people to promote the welfare of senior
         citizens [syn: Association for the Advancement of Retired
         Persons, AARP]

The Free On-line Dictionary of Computing (19 January 2023):

Apple Address Resolution Protocol
AARP

    (AARP) Apple's system to allow AppleTalk
   protocol to work over networks other than LocalTalk, such
   as Ethernet or Token Ring.  AppleTalk nodes announce
   their presence to the network so that other nodes can address
   messages to them.  AARP maps between AppleTalk addresses and
   other schemes.  It is actually a general address mapping
   protocol that can be used to map between addresses at any
   protocol level.

   [G. Sidhu, R. Andrews, and A. Oppenheimer, "Inside AppleTalk",
   Addison Wesley, 1990].

   (2006-04-18)