NOUN (1)

1. imaginary people who live on the planet Mars;


ADJECTIVE (1)

1. of or relating to the planet Mars (or its fictional inhabitants);

The Collaborative International Dictionary of English v.0.48:

Martian \Mar"tian\, prop. a. [L. Martius.]
   Of or pertaining to Mars, the Roman god of war, or to the
   planet bearing his name; martial.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Martian \Mar"tian\, prop. n.
   An inhabitant of the planet Mars; -- fictional or
   hypothetical. --Du Maurier.
   [Webster 1913 Suppl.]

   Note: In science fiction, it has often been postulated that
         there are intelligent creatures living on Mars, but no
         strong evidence of any form of life on Mars has been
         observed up to the end of 1998.

WordNet (r) 3.0 (2006):

Martian
    adj 1: of or relating to the planet Mars (or its fictional
           inhabitants)
    n 1: imaginary people who live on the planet Mars

The Jargon File (version 4.4.7, 29 Dec 2003):

martian
 n.

    A packet sent on a TCP/IP network with a source address of the test
    loopback interface [127.0.0.1]. This means that it will come back labeled
    with a source address that is clearly not of this earth. ?The domain server
    is getting lots of packets from Mars. Does that gateway have a martian
    filter?? Compare Christmas tree packet, Godzillagram.


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

Martian

   Packets that turn up unexpectedly on the wrong network
   because of bogus routing entries.  Also a packet which has
   an altogether bogus (non-registered or ill-formed) internet
   address, such as the test loopback interface [127.0.0.1].
   Such a packet will come back labelled with a source address
   that is clearly not of this earth.  "The domain server is
   getting lots of packets from Mars.  Does that gateway have a
   martian filter?"

   [Jargon File]