mars

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]

Source: The Collaborative International Dictionary of English