mer·​cu·​ry | \ ˈmər-kyə-rē How to pronounce mercury (audio) , -k(ə-)rē \
plural mercuries

Definition of mercury

1a capitalized : a Roman god of commerce, eloquence, travel, cunning, and theft who serves as messenger to the other gods — compare hermes
b often capitalized, archaic : a bearer of messages or news or a conductor of travelers
2 [Middle English mercurie, from Medieval Latin mercurius, from Latin, the god]
a : a silver-white poisonous heavy metallic element that is liquid at ordinary temperatures and is used especially in batteries, in dental amalgam, and in scientific instruments

called also quicksilver

— see Chemical Elements Table
b : the column of mercury in a thermometer or barometer also : temperature the mercury rose above 70 degrees
3 capitalized : the planet nearest the sun — see Planets Table

Examples of mercury in a Sentence

In the summer, the mercury can reach over 100 degrees Fahrenheit.
Recent Examples on the Web In 1980 and 1988, the mercury reached or topped 90 for a record three weeks straight. Ian Livingston, Washington Post, "D.C. streak of hot weather hits historic territory, and the worst may be yet to come," 9 July 2020 Attorneys general from more than a dozen states, led by Massachusetts Attorney General Maura Healey, are intervening to protect Obama-era limits on power plants’ mercury and air toxics from a coal industry challenge. Josh Siegel, Washington Examiner, "Daily on Energy, presented by API: Stacey Abrams-led group accuses utilities of holding up climate policy in the South," 23 June 2020 The East Lansing waste-water treatment plant mishandled a mercury spill at the plant. Megan Garber, The Atlantic, "The National Emergency at Your Doorstep," 11 July 2020 But near one of those mines, Greens Creek in Alaska, there have been reports of high levels of mercury in the surrounding area. Jack Brook, The Christian Science Monitor, "Conservation vs. copper: Minnesota town debates its future with a mine," 2 July 2020 The pretty red mineral, which produces such lovely shades when mixed with iron oxide, is actually mercury sulfide. Kiona N. Smith, Ars Technica, "Mercury and algal blooms poisoned Maya reservoirs at Tikal," 30 June 2020 Skin-lightening products, which often contain hydroquinone or mercury, remain largely unregulated and researchers are still determining the full extent of the risks for people who use them. Thatiana Diaz,, "The Skin-Lightening Industry Is Facing A Long Overdue Reckoning," 26 June 2020 Prospectors face all the usual environmental hazards of gold mining, principally exposure to mercury. Paul Salopek, National Geographic, "Hunting for particles of gold in the jungles of Southeast Asia," 24 June 2020 Even small-scale plants emit pollutants that include mercury, lead, and harmful particulates. Jane Braxton Little, Wired, "The Debate Over Burning Dead Trees to Create Biomass Energy," 27 June 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'mercury.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of mercury

14th century, in the meaning defined at sense 1a

History and Etymology for mercury

Latin Mercurius, Roman god and the planet

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Time Traveler for mercury

Time Traveler

The first known use of mercury was in the 14th century

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Statistics for mercury

Last Updated

28 Jul 2020

Cite this Entry

“Mercury.” Dictionary, Merriam-Webster, Accessed 8 Aug. 2020.

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How to pronounce mercury (audio)

English Language Learners Definition of mercury

: a silver metal that is liquid at normal temperatures
: the mercury in a thermometer that shows the air's temperature
: the planet that is closest to the sun


mer·​cu·​ry | \ ˈmər-kyə-rē How to pronounce mercury (audio) \

Kids Definition of mercury

1 : a heavy silvery white poisonous metallic chemical element that is liquid at ordinary temperatures
2 : the column of mercury in a thermometer or barometer
3 capitalized : the planet that is nearest the sun and has a diameter of about 3000 miles (4700 kilometers)


mer·​cu·​ry | \ ˈmər-kyə-rē, -k(ə-)rē How to pronounce mercury (audio) \
plural mercuries

Medical Definition of mercury

1 : a heavy silver-white poisonous metallic element that is liquid at ordinary temperatures and used especially in scientific instruments symbol Hg

called also quicksilver

— see Chemical Elements Table
2 : a pharmaceutical preparation containing mercury or a compound of it

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More from Merriam-Webster on mercury

Spanish Central: Translation of mercury

Nglish: Translation of mercury for Spanish Speakers

Britannica English: Translation of mercury for Arabic Speakers Encyclopedia article about mercury

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