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 If a company wanted to put mercury or cocaine in their miracle drug, the Bureau of Chemistry had no problem with that — so long as it was mentioned on the label. New York Times, "How Humanity Gave Itself an Extra Life," 27 Apr. 2021 Thiomersal is a mercury-containing preservative used in some vaccines, such as the multidose flu vaccines. Dr. Keith Roach, oregonlive, "Dear Doctor: I’m extremely allergic to this preservative. Is it in COVID-19 vaccines?," 24 Apr. 2021 So adding mercury to lead gives a physical reaction. Nadja Sayej, Forbes, "Jac Lahav On Alchemy, Ancient Ruins And Abstraction," 21 Apr. 2021 The mercury will hit 77 on Tuesday then slip to 67 on Wednesday and 63 on Thursday and Friday. Gary Robbins, San Diego Union-Tribune, "Work week to start off warm then quickly turn cool across greater San Diego," 18 Apr. 2021 Chinese women in the Tang Dynasty fashioned rouge out of pomegranate, safflower, and cinnabar, a mineral containing toxic mercury. Linda Wells, Town & Country, "This Will Make You Blush," 16 Apr. 2021 Definitely, especially since the bay is known to have harbored heavy metals like mercury, partly as a long after-effect of the Gold Rush. Taylor Kate Brown, San Francisco Chronicle, "MicroClimates: 'The power of mud'," 16 Apr. 2021 This inexpensive fish is high in heart-healthy omega-3 fatty acids but low in mercury. Stefani Sassos, Ms, Rdn, Cso, Good Housekeeping, "8 Healthy Foods That Are High in Vitamin D," 13 Apr. 2021 This model can hold up to 18 cups and filters out particulates like chlorine and mercury from tap water. Hanna Horvath, NBC News, "My most important work-from-home accessory is a water cooler," 8 Apr. 2021

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

6 May 2021

Cite this Entry

“Mercury.” Dictionary, Merriam-Webster, Accessed 18 May. 2021.

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More Definitions for mercury



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

More from Merriam-Webster on mercury

Nglish: Translation of mercury for Spanish Speakers

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

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