|—n , pl -ries|
|1.||quicksilver, Also called: hydrargyrum a heavy silvery-white toxic liquid metallic element occurring principally in cinnabar: used in thermometers, barometers, mercury-vapour lamps, and dental amalgams. Symbol: Hg; atomic no: 80; atomic wt: 200.59; valency: 1 or 2; relative density: 13.546; melting pt: --38.842°C; boiling pt: 357°C|
|2.||See dog's mercury any plant of the euphorbiaceous genus Mercurialis|
|3.||archaic a messenger or courier|
|[C14: from Latin Mercurius messenger of Jupiter, god of commerce; related to merx merchandise]|
mercury mer·cu·ry (mûr'kyə-rē)
A silvery-white poisonous metallic element, liquid at room temperature and used in thermometers. Atomic number 80; atomic weight 200.59; melting point -38.83°C; boiling point 356.73°C; specific gravity 13.546 (at 20°C); valence 1, 2. Also called hydrargyrum.
|mercury (mûr'kyə-rē) Pronunciation Key
A silvery-white, dense, poisonous metallic element that is a liquid at room temperature and is used in thermometers, barometers, batteries, and pesticides. Atomic number 80; atomic weight 200.59; melting point -38.87°C; boiling point 356.58°C; specific gravity 13.546 (at 20°C); valence 1, 2. See Periodic Table.
Our Living Language : Like a few other elements, mercury has a chemical symbol, Hg, that bears no resemblance to its name. This is because Hg is an abbreviation of the Latin name of the element, which was hydrargium. This word in turn was taken over from Greek, where it literally meant "water-silver." With this name the Greeks were referring to the fact that mercury is a silvery liquid at room temperature, rather than a solid like other metals. Similarly, an older English name for this element is quicksilver, which means "living silver," referring to its ability to move like a living thing. (The word quick used to mean "alive," as in the Biblical phrase "the quick and the dead.") The name mercury refers to the fact that the element flows about quickly: the name comes from the Roman god Mercury, who was the swift-footed messenger of the gods.
The planet closest to the Sun and the second smallest in the solar system. Mercury is a terrestrial or inner planet, second in density only to Earth, with a rugged, heavily-cratered surface similar in appearance to Earth's Moon. Its rotational period of 58.6 days is two-thirds of its 88-day orbital period, thus, it makes three full axial rotations every two years. Mercury's atmosphere is almost nonexistent; this fact, which produces rapid radiational cooling on its dark side, together with its proximity to the Sun, gives it a temperature range greater than any other planet in the solar system, from 466° to -184°C (870° to -300°F). Because it is so close to the Sun, Mercury is only visible shortly before sunrise or after sunset, and observation is further hindered by the fact that its light must pass obliquely through the lower atmosphere where it is distorted or filtered by dust and pollution. See Table at solar system.
In astronomy, the planet closest to the sun, named after the fleet-footed messenger of the Roman gods (see under “Mythology and Folklore”) because of its swift movement in its orbit. Mercury takes only eighty-eight days to go around the sun. (See solar system.)
In chemistry, a heavy, silvery metallic element, a liquid at normal temperatures. Mercury expands or contracts rapidly in response to changes in temperature and therefore was once widely used in thermometers.
Note: The term mercury is used figuratively in such expressions as “The mercury's rising” to mean that the temperature is going up.