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 While the mercury climbed into the 80s twice this week, expect weekend highs to feel more like fall as the National Weather Service’s forecast calls for highs near 60 both Saturday and Sunday. Mike Rose, cleveland, 15 Oct. 2021 Behind the dramatic reversal in conditions is a ridge of high pressure building from the southwest, driving up the mercury and banishing clouds, according to Sweet. Lila Seidman, Los Angeles Times, 29 Sep. 2021 In the southern Spanish province of Granada, where the mercury rose to 113.7 F, few people ventured outside. Jennifer O'mahony, USA TODAY, 14 Aug. 2021 For example, in a highly controversial Obama-era air pollution regulation targeting mercury emissions, the overwhelming majority of the benefits in EPA’s analysis came from reducing a different pollutant, particulate matter. James Broughel, Forbes, 28 May 2021 Barlow did rule that the BLM’s analysis of mercury emissions was adequate. Brian Maffly, The Salt Lake Tribune, 27 Mar. 2021 While there are no specific limits set for infant foods, the EPA and FDA set an upper limit of 2 parts per billion of inorganic mercury in drinking water, and 5 parts per billion for cadmium. Sandee Lamotte, CNN, 29 Sep. 2021 One example of a hazardous product is those that contain mercury, such as thermometers, fluorescent lights or the weights in old grandfather clocks. Sarah Bowman, The Indianapolis Star, 3 Sep. 2021 Plunging mercury in Texas led to a spike in natural-gas and power prices in February. Joe Wallace, WSJ, 27 July 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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Learn More About mercury

Time Traveler for mercury

Time Traveler

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

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Dictionary Entries Near mercury

mercurous chloride


Mercury's staff

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Statistics for mercury

Last Updated

21 Oct 2021

Cite this Entry

“Mercury.” Dictionary, Merriam-Webster, Accessed 21 Oct. 2021.

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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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