"Jovian" means relating to the planet Jupiter (i.e. "of Jove"), the fifth planet from the sun. Jupiter is the largest planet in the solar system, with twice as much mass as all the other planets combined. With a 69,000km radius, it is 11 times the diameter of Earth (and 11^3 the volume); its Great Red Spot, a 400+ year old storm, could contain 3 Earths. Jupiter has 16 moons, of which 4 are very large (the Galilean satellites, discovered by Galileo in 1610) and the other 12 are minor. The four large moons are Io, Europa, Ganymede, and Callisto. Of the 12 minor moons, 4 are closer than Io and 8 are further away than Callisto.

More Jupiter Info can be found at these links:
JPL site
Arizona site
Galileo Site