The Collaborative International Dictionary of English v.0.48:

Nat \Nat\ (n[aum]t), adv.
   Not. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Nat \Nat\ [For ne at.]
   Not at; nor at. [Obs.] --haucer.
   [1913 Webster]

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

NAT
       [IP] Network Address Translator (RFC 1631, IP)


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

Network Address Translation
NAT
Network Address Translator

    (NAT, or Network Address Translator, Virtual LAN)
   A technique in which a router or firewall rewrites the
   source and/or destination Internet addresses in a packet as
   it passes through, typically to allow multiple hosts to
   connect to the Internet via a single external IP address.
   NAT keeps track of outbound connections and distributes
   incoming packets to the correct machine.

   NAT is an alternative to adopting IPv6 (IPng).  It allows
   the same IP addresses (10.x.x.x is the conventional range) to
   be used on many private local networks while requiring only
   one of the increasingly scarce public addresses to be
   allocated to each private network.

   NAT does not however allow an external service to initiate a
   TCP connection to an internal host, nor does it support
   stateless protocols based on UDP well unless the router
   software has extensions to support each specific protocol.

   (2005-09-18)