Jupiter

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Roman Mythology The supreme god, patron of the Roman state and brother and husband of Juno. He came to be identified with the Greek Zeus.
• noun Astronomy The fifth planet from the sun, the largest and most massive in the solar system, having a sidereal period of revolution about the sun of 11.86 years at a mean distance of 778.6 million kilometers (483.8 million miles), a mean diameter of approximately 143,000 kilometers (89,000 miles), and a mass approximately 320 times that of Earth.

from The Century Dictionary.

• noun In Roman mythology, the supreme deity, the parallel of the Greek Zeus, and the embodiment of the might and national dignity of the Romans.
• noun The brightest of the superior planets, and the largest body of the solar system except the sun itself.
• noun In alchemy, tin, which was supposed to be under the control of the planet Jupiter.
• noun In heraldry, the tincture azure or blue in blazoning by the planets. See blazon, n.
• noun In zoology, a finback whale. Also called Jupiter-fish.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Rom. Myth.) The supreme deity, king of gods and men, and reputed to be the son of Saturn and Rhea; Jove. He corresponds to the Greek Zeus.
• noun (Astron.) One of the planets, being the fifth from the sun, the brightest except Venus, and the largest of them all, its mean radius being about 43,345 miles (69,758 kilometers), almost exactly one-tenth that of the sun. It revolves about the sun in 4,332.6 days, at a mean distance of 5.2025 from the sun (778,140,000 km), the earth's mean distance (the astronomical unit) being taken as unity. It has a mass of 1.901 x 1027 kg, about one-thousandth that of the sun, and more than the remainder of the planets combined. It has an average solar day equal to 9.842 earth hours. The rapid revolution causes a noticeable flattening at the poles; the diameter at the equator is 71,370 km, and at the poles 66,644 km.
• noun (Bot.) the cloverlike Anthyllis Barba-Jovis.
• noun (Bot.) the common mullein; -- so called from its long, rigid spike of yellow blossoms.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun astronomy The fifth and by far the largest planet in the Solar System, a gas giant, represented by the symbol ♃ in astronomy. Jupiter is known for its Great Red Spot and many moons including the Galilean moons.
• proper noun Roman mythology The King of the Gods, also called Jove. Equivalent to the Greek Zeus, Jupiter was one of the children of Saturn.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (Roman mythology) supreme god of Romans; counterpart of Greek Zeus
• noun the largest planet and the 5th from the sun; has many satellites and is one of the brightest objects in the night sky