The Collaborative International Dictionary of English v.0.48:

Mars \Mars\ (m[aum]rz), prop. n. [L. Mars, gen. Martis, archaic
   Mavors, gen. Mavortis.]
   1. (Rom. Myth.) The god of war and husbandry.
      [1913 Webster]

   2. (Astron.) One of the planets of the solar system, the
      fourth in order from the sun, or the next beyond the
      earth, having a diameter of about 4,200 miles, a period of
      687 days, and a mean distance of 141,000,000 miles. It is
      conspicuous for the redness of its light.
      [1913 Webster]

   3. (Alchemy) The metallic element iron, the symbol of which
      [male] was the same as that of the planet Mars. [Archaic]
      --Chaucer.
      [1913 Webster]

   Mars brown, a bright, somewhat yellowish, brown.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Mars
    n 1: a small reddish planet that is the 4th from the sun and is
         periodically visible to the naked eye; minerals rich in
         iron cover its surface and are responsible for its
         characteristic color; "Mars has two satellites" [syn:
         Mars, Red Planet]
    2: (Roman mythology) Roman god of war and agriculture; father of
       Romulus and Remus; counterpart of Greek Ares

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "Mars":
   Agdistis, Amor, Aphrodite, Apollo, Apollon, Ares, Artemis, Ate,
   Athena, Bacchus, Bellona, Ceres, Cora, Cronus, Cupid, Cybele,
   Demeter, Despoina, Diana, Dionysus, Dis, Earth, Enyo, Eros, Gaea,
   Gaia, Ge, Great Mother, Hades, Helios, Hephaestus, Hera, Here,
   Hermes, Hestia, Hymen, Hyperion, Jove, Juno, Jupiter,
   Jupiter Fidius, Jupiter Fulgur, Jupiter Optimus Maximus,
   Jupiter Pluvius, Jupiter Tonans, Kore, Kronos, Magna Mater,
   Mercury, Minerva, Mithras, Momus, Neptune, Nike, Odin, Olympians,
   Olympic gods, Ops, Orcus, Persephassa, Persephone, Phoebus,
   Phoebus Apollo, Pluto, Poseidon, Proserpina, Proserpine, Rhea,
   Saturn, Tellus, Tiu, Tyr, Uranus, Venus, Vesta, Vulcan, Woden,
   Wotan, Zeus, asteroid, inferior planet, major planet, minor planet,
   planet, planetoid, secondary planet, solar system, superior planet,
   terrestrial planet, wanderer



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

Mars
 n.

    A legendary tragic failure, the archetypal Hacker Dream Gone Wrong. Mars
    was the code name for a family of PDP-10-compatible computers built by
    Systems Concepts (now, The SC Group): the multi-processor SC-30M, the small
    uniprocessor SC-25, and the never-built superprocessor SC-40. These
    machines were marvels of engineering design; although not much slower than
    the unique Foonly F-1, they were physically smaller and consumed less
    power than the much slower DEC KS10 or Foonly F-2, F-3, or F-4 machines.
    They were also completely compatible with the DEC KL10, and ran all KL10
    binaries (including the operating system) with no modifications at about
    2--3 times faster than a KL10.

    When DEC cancelled the Jupiter project in 1983 (their followup to the
    PDP-10), Systems Concepts should have made a bundle selling their machine
    into shops with a lot of software investment in PDP-10s, and in fact their
    spring 1984 announcement generated a great deal of excitement in the PDP-10
    world. TOPS-10 was running on the Mars by the summer of 1984, and TOPS-20
    by early fall. Unfortunately, the hackers running Systems Concepts were
    much better at designing machines than at mass producing or selling them;
    the company allowed itself to be sidetracked by a bout of perfectionism
    into continually improving the design, and lost credibility as delivery
    dates continued to slip. They also overpriced the product ridiculously;
    they believed they were competing with the KL10 and VAX 8600 and failed
    to reckon with the likes of Sun Microsystems and other hungry startups
    building workstations with power comparable to the KL10 at a fraction of
    the price. By the time SC shipped the first SC-30M to Stanford in late
    1985, most customers had already made the traumatic decision to abandon the
    PDP-10, usually for VMS or Unix boxes. Most of the Mars computers built
    ended up being purchased by CompuServe.

    This tale and the related saga of Foonly hold a lesson for hackers: if
    you want to play in the Real World, you need to learn Real World moves.


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

Mars

   A legendary tragic failure, the archetypal Hacker Dream Gone
   Wrong.  Mars was the code name for a family of PDP-10
   compatible computers built by Systems Concepts (now, The SC
   Group): the multi-processor SC-30M, the small uniprocessor
   SC-25M, and the never-built superprocessor SC-40M.  These
   machines were marvels of engineering design; although not much
   slower than the unique Foonly F-1, they were physically
   smaller and consumed less power than the much slower DEC KS10
   or Foonly F-2, F-3, or F-4 machines.  They were also
   completely compatible with the DEC KL10, and ran all KL10
   binaries (including the operating system) with no
   modifications at about 2--3 times faster than a KL10.

   When DEC cancelled the Jupiter project in 1983, Systems
   Concepts should have made a bundle selling their machine into
   shops with a lot of software investment in PDP-10s, and in
   fact their spring 1984 announcement generated a great deal of
   excitement in the PDP-10 world.  TOPS-10 was running on the
   Mars by the summer of 1984, and TOPS-20 by early fall.

   Unfortunately, the hackers running Systems Concepts were much
   better at designing machines than at mass producing or selling
   them; the company allowed itself to be sidetracked by a bout
   of perfectionism into continually improving the design, and
   lost credibility as delivery dates continued to slip.  They
   also overpriced the product ridiculously; they believed they
   were competing with the KL10 and VAX 8600 and failed to reckon
   with the likes of Sun Microsystems and other hungry startups
   building workstations with power comparable to the KL10 at a
   fraction of the price.

   By the time SC shipped the first SC-30M to Stanford in late
   1985, most customers had already made the traumatic decision
   to abandon the PDP-10, usually for VMS or Unix boxes.  Most of
   the Mars computers built ended up being purchased by
   CompuServe.

   This tale and the related saga of Foonly hold a lesson for
   hackers: if you want to play in the Real World, you need to
   learn Real World moves.

   [Jargon File]


U.S. Gazetteer Places (2000):

Mars, PA -- U.S. borough in Pennsylvania
   Population (2000):    1746
   Housing Units (2000): 715
   Land area (2000):     0.446948 sq. miles (1.157591 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.446948 sq. miles (1.157591 sq. km)
   FIPS code:            47672
   Located within:       Pennsylvania (PA), FIPS 42
   Location:             40.696594 N, 80.012205 W
   ZIP Codes (1990):     16046
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Mars, PA
    Mars