Martial And Jovial

An inflected Latin noun has both a root and an ending. Thus, the accusative case of Mars is Martem.

Mart- = root;
-em = ending. 

Since the nominative case does not always give the root, both nominative and genitive cases are cited. Thus: Mars, Martis.

The root, Mart-, generated the English adjectives, "martial" and "Martian." The root, Jov-, generated "jovial" and "Jovian." The root, Vener-, generated "venerate," "venerable," "venereal" and "Venerian" (not "Venusian").

ERB's John Carter, a soldier, regards Mars as his god of war and finds that the Martians are martial. Robert Heinlein once wrote:

"...the sharp, bright stars of the Martial sky..."
-Robert Heinlein, "The Green Hills of Earth" IN Heinlein, The Green Hills Of Earth (London, 1967), pp. 131-140 at p. 135.

Poul Anderson once wrote:

"...the Jovial colonists..."
-Poul Anderson, The Snows Of Ganymede (New York, 1958), Chapter 3, p. 15.