People's Dictionary of the Bible 
Mars' Hill ( März Hĭll ), or Areopagus ( Ăr'E- Ŏp'A-Gŭs or Â'Re-Ŏp'A-Gŭs ). Acts 17:19; Acts 17:34. This was a rocky height in Athens, opposite the western end of the Acropolis. From this spot Paul delivered his address to the men of Athens. Acts 17:22-31. He also "disputed" in the "market," or Agora, "daily," 17:17, which was south of the Areopagus, in the valley lying between this hill and those of the Acropolis, the Pnyx, and the Museum.
Webster's Dictionary 
(1): ( n.) The metallic element iron, the symbol of which / was the same as that of the planet Mars.
(2): ( n.) 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.
(3): ( n.) The god of war and husbandry.
King James Dictionary 
M`ARS, n. In mythology, the god of war in modern usage, a planet and in the old chimistry, a term for iron.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
a contraction of Mavers or Mavors, in the Oscan or Sabine language Mamers, Greek Avers, is the name of the Roman and Greek god of war, or, better, of battles.
(1) With the Romans this divinity is surnamed Gradivus (=Grandis Divus, the great god), also Silvalus, and appears to have been originally an agricultural deity — propitiatory offerings were presented to him as the guardian of fields and flocks; but as the fierce shepherds who founded the city of Rome were even more addicted to martial than to pastoral pursuits, one can easily understand how Mars Silvanus should have, in the course of time, become the "God of War." Mars, who was a perfect representation of the stern, relentless, and even cruel valor of the old Romans, was held in the highest honor. He ranked next to Jupiter; like him he bore the venerable epithet of Father (Marspiter); he was one of the three tutelary divinities of the city, to each of whom Numa appointed a flamen; nay, he was said to be the father of Romulus himself (by Rhea Silvia, the priestess of Vesta), and was thus believed to be the real progenitor of the Roman people. He had a sanctuary on the Quirinal; and the hill received its name from his surname, Quirinus, the most probable meaning of which is the spear-armed. It was under this designation that he was invoked as the protector of the Quirites (citizens) — in other words, of the state, The principal animals sacred to him were the wolf and the horse. He had many temples at Rome, the most celebrated of which was that outside the Porta Capena, on the Appian Road. The Campus Martius, where the Romans practiced athletic and military exercises, was named after him; so was the month of March (Martins). the first month of the Roman year. The Ludi Martiales (games held in his honor) were celebrated every year in the circus on the 1st of August.
(2) ARES, the Greek god of war, was the son of Zeus and Hera, and the favorite of Aphrodite, who bore him several children. He is represented in Greek poetry as a most sanguinary divinity, delighting in war for its own sake, and in the destruction of men. Before him into battle goes his sister Eris (Strife); along with him are his sons and companions, Deimos (Horror), and Phobos (Fear). He does not always adhere to the same side, like the great Athena, but inspires now the one, now the other. He is not always victorious. Diomede wounded him, and in his fall, says Homer, "he roared like nine or ten thousand warriors together." Such a representation would have been deemed blasphemous by the ancient Roman mind, imbued as it was with a solemn, Hebrew-like reverence for its gods. The worship of Ares was never very prevalent in Greece; it is believed to have been imported from Thrace. There and in Scythia were its great seats, and there Ares was believed to have his chief home. He had, however, temples or shrines at Athens, Sparta, Olympia, and other places. On statues and reliefs he is represented as a person of great muscular power, and either naked or clothed with the chlamys. — Chambers, Cyclop. s.v.; Smith, Dict. Gr. and Romans Biog. and Mythol. vol. 2, s.v.; Vollmer, Mythol. W Ö rterbuch, s.v.
The Nuttall Encyclopedia 
The exterior planet of the Solar system, nearest the earth, of one-half its diameter, with a mean distance from the sun of 141,000,000 m., round which it takes 686 days to revolve, in a somewhat centric orbit, and 24½ hours to revolve on its own axis, which inclines to its equator at an angle of 29°; examination of it shows that there is four times as much land as water in it; it is accompanied by two moons, an outer making a revolution round it in 30 hours 18 minutes, and an inner in 7 hours and 38 minutes; they are the smallest heavenly bodies known to science.