go to the dogs, rain cats and dogs

1.  mercury(n = noun.substance) atomic number 80, hg, hydrargyrum, quicksilver - a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures;
is a kind of metal, metallic element
Derived forms adjective mercurial₄, adjective mercuric₁, adjective mercurous₁

2.  mercury(n = noun.person) - (Roman mythology) messenger of Jupiter and god of commerce; counterpart of Greek Hermes;
is a kind of roman deity
Derived form adjective mercurial₃

3.  mercury(n = noun.object) - the smallest planet and the nearest to the sun;
is a kind of inferior planet, terrestrial planet
is a member of solar system

4.  mercury(n = noun.attribute) - temperature measured by a mercury thermometer; "the mercury was falling rapidly"
is a kind of temperature

1.  A Latin god of commerce and gain; -- treated by the poets as identical with the Greek Hermes, messenger of the gods, conductor of souls to the lower world, and god of eloquence. [1913 Webster]

2.  A metallic element mostly obtained by reduction from cinnabar, one of its ores. It is a heavy, opaque, glistening liquid (commonly called quicksilver), and is used in barometers, thermometers, etc. Specific gravity 13.6. Symbol Hg (Hydrargyrum). Atomic weight 199.8. Mercury has a molecule which consists of only one atom. It was named by the alchemists after the god Mercury, and designated by his symbol, 1913 Webster]
" Mercury forms alloys, called amalgams, with many metals, and is thus used in applying tin foil to the backs of mirrors, and in extracting gold and silver from their ores. It is poisonous, and is used in medicine in the free state as in blue pill, and in its compounds as calomel, corrosive sublimate, etc. It is the only metal which is liquid at ordinary temperatures, and it solidifies at about -39" [1913 Webster]

3.  One of the planets of the solar system, being the one nearest the sun, from which its mean distance is about 36,000,000 miles. Its period is 88 days, and its diameter 3,000 miles. [1913 Webster]

4.  A carrier of tidings; a newsboy; a messenger; hence, also, a newspaper. [1913 Webster]

5.  Sprightly or mercurial quality; spirit; mutability; fickleness. [1913 Webster]
"He was so full of mercury that he could not fix long in any friendship, or to any design." [1913 Webster]

6.  A plant (Mercurialis annua), of the Spurge family, the leaves of which are sometimes used for spinach, in Europe. [1913 Webster]
" The name is also applied, in the United States, to certain climbing plants, some of which are poisonous to the skin, esp. to the Rhus Toxicodendron, or poison ivy." [1913 Webster]

   To wash with a preparation of mercury. B. Jonson. [1913 Webster]

mercury, n.
1 Chem. a silvery-white heavy liquid metallic element occurring naturally in cinnabar and used in barometers, thermometers, and amalgams; quicksilver.

Idiom:
mercury vapour lamp a lamp in which light is produced by an electric discharge through mercury vapour.

Usage:
Symb.: Hg.
2 (Mercury) the planet nearest to the sun.
3 any plant of the genus Mercurialis, esp. M. perenne.

Derivative:
mercuric adj. mercurous adj.

Etymology:
ME f. L Mercurius messenger of the gods and god of traders f. merx mercis merchandise

N  traveler, wayfarer, voyager, itinerant, passenger, commuter, tourist, excursionist, explorer, adventurer, mountaineer, hiker, backpacker, Alpine Club, peregrinator, wanderer, rover, straggler, rambler, bird of passage, gadabout, gadling, vagrant, scatterling, landloper, waifs and estrays, wastrel, foundling, loafer, tramp, tramper, vagabond, nomad, Bohemian, gypsy, Arab, Wandering Jew, Hadji, pilgrim, palmer, peripatetic, somnambulist, emigrant, fugitive, refugee, beach comber, booly, globegirdler, globetrotter, vagrant, hobo, night walker, sleep walker, noctambulist, runabout, straphanger, swagman, swagsman, trecker, trekker, zingano, zingaro, runner, courier, Mercury, Iris, Ariel, comet, pedestrian, walker, foot passenger, cyclist, wheelman, rider, horseman, equestrian, cavalier, jockey, roughrider, trainer, breaker, driver, coachman, whip, Jehu, charioteer, postilion, postboy, carter, wagoner, drayman, cabman, cabdriver, voiturier, vetturino, condottiere, engine driver, stoker, fireman, guard, chauffeur, conductor, engineer, gharry-wallah, gari-wala, hackman, syce, truckman, on the road.

N  velocity, speed, celerity, swiftness, rapidity, eagle speed, expedition, pernicity, acceleration, haste, spurt, rush, dash, race, steeple chase, smart rate, lively rate, swift rate, rattling rate, spanking rate, strapping rate, smart pace, lively pace, swift pace, rattling pace, spanking pace, strapping pace, round pace, flying, flight, lightning, greased lightning, light, electricity, wind, cannon ball, rocket, arrow, dart, hydrargyrum, quicksilver, telegraph, express train, torrent, eagle, antelope, courser, race horse, gazelle, greyhound, hare, doe, squirrel, camel bird, chickaree, chipmunk, hackee, ostrich, scorcher, Mercury, Ariel, Camilla, Harlequin, log, log line, speedometer, odometer, tachometer, strobe, radar speed detector, radar trap, air speed gauge, wind sock, wind speed meter, pedometer, fast, speedy, swift, rapid, quick, fleet, aliped, nimble, agile, expeditious, express, active, flying, galloping, light footed, nimble footed, winged, eagle winged, mercurial, electric, telegraphic, light-legged, light of heel, swift as an arrow, quick as lightning, quick as a thought, swiftly, with speed, apace, at a great rate, at full speed, at railway speed, full drive, full gallop, posthaste, in full sail, tantivy, trippingly, instantaneously, under press of sail, under press of canvas, under press of sail and steam, velis et remis, on eagle's wing, in double quick time, with rapid strides, with giant strides, a pas de geant, in seven league boots, whip and spur, ventre a terre, as fast as one's legs will carry one, as fast as one's heels will carry one, as fast as one can lay legs to the ground, at the top of one's speed, by leaps and bounds, with haste, vires acquirit eundo, I'll put a girdle about the earth in forty minutes, swifter than arrow from the Tartar's bow, go like a bat out of hell, tempus fugit.

N  messenger, envoy, emissary, legate, nuncio, internuncio, ambassador, marshal, flag bearer, herald, crier, trumpeter, bellman, pursuivant, parlementaire, apparitor, courier, runner, dak, estafette, Mercury, Iris, Ariel, commissionaire, errand boy, chore boy, newsboy, mail, overnight mail, express mail, next-day delivery, post, post office, letter bag, delivery service, United Parcel Service, UPS, Federal Express, Fedex, telegraph, telephone, cable, wire (electronic information transmission), carrier pigeon, (news) 532 reporter, gentleman of the press, representative of the press, penny-a-liner, special correspondent, own correspondent, spy, scout, informer.

bichloride of mercury, dog mercury, dog's mercury, fulminate of mercury, fulminating mercury, herb mercury, herbs mercury, mercury barometer, mercury bichloride, mercury cell, mercury chloride, mercury fulminate, mercury poisoning, mercury program, mercury thermometer, millimeter of mercury, poison mercury, three-seeded mercury