mercury

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noun mer·cu·ry \ ˈmər-kyə-rē , -k(ə-)rē \

Definition of mercury

plural mercuries

1 a 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

[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

See mercury defined for English-language learners

See mercury defined for kids

Examples of mercury in a Sentence

In the summer, the mercury can reach over 100 degrees Fahrenheit.

Recent Examples of mercury from the Web

On July 5, 2012, the mercury soared to 105 at Northerly Island while Midway and O'Hare both recorded 103.

— tom skilling, chicagotribune.com, "Ask Tom: Why is it hotter at Midway than at other weather-reporting stations?," 25 Aug. 2017
Bring a sweater along with those special glasses because the mercury could dip as the moon’s shadow crosses the land.

— brian k sullivan, Bloomberg.com, "Eclipse Turning Day Into Night to Send Temperatures Tumbling," 18 Aug. 2017
And by Sunday, the mercury will be creeping up again, with lows in the mid-60s and highs in the 85-to-90 range, predicted to last at least through Thursday.

— christine clarridge, The Seattle Times, "When will Seattle’s wildfire haze blow away? No one knows, but heat will persist," 4 Aug. 2017
Dr. Gunter points out that some skin-lightening products contain substances like mercury or steroids, which—

— anthea levi, Health.com, "Why You Really Don’t Need to Use Highlighter on Your Vulva," 27 July 2017
This time of year, when the mercury hits the high 90s, most of us tuck nursery buying trips in the back recesses of our gardener’s mind.

— paul cappiello, The Courier-Journal, "A stunning glimpse into the contrast offered by today’s nursery industry," 21 July 2017
Karen went to a new doctor, who told her that there’s increasing consensus that lupus can be brought on by environmental triggers, including exposure to contaminants and chemicals, like cigarette smoke, silica, and mercury.

— danielle jackson, Longreads, "The St. Louis Suburbs Bear the Cost of America’s Nuclear Past," 15 July 2017
The mercury was 90 at Gillespie Field, 88 at San Diego Zoo Safari Park, and 88 at Poway.

— gary robbins, sandiegouniontribune.com, "Heat wave will peak Monday with inland temperatures in the 100s," 25 June 2017
The mercury rose in 1978 to find Heart playing stadiums, to more than 100,000 fans at Texxas Jam (the two Xs are intentional) after rocking some 300,000 plus at Cal Jam II.

— matt wake, AL.com, "A guitar Heart took to '70s success has an Alabama connection," 20 June 2017

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.

Origin and Etymology of mercury

Latin Mercurius, Roman god and the planet

NEW! Time Traveler

First Known Use: 14th century

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MERCURY Defined for English Language Learners

mercury

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noun

Definition of mercury for English Language Learners

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

MERCURY Defined for Kids

mercury

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noun mer·cu·ry \ ˈmər-kyə-rē \

Definition of mercury for Students

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)

Medical Dictionary

mercury

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noun mer·cu·ry \ ˈmər-kyə-rē, -k(ə-)rē \

medical Definition of mercury

plural mercuries

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

Biographical Note for mercury

Mercury, Roman mythological character. In Roman mythology Mercury became identified with the Greek god Hermes. This god was known especially as the fleet-footed messenger of the gods. He was also the god of science and the arts and the patron of travelers and athletes. He is typically represented in art as a young man wearing a winged helmet and winged sandals and bearing a caduceus. The metal mercury was named after him most probably because he symbolizes mobility.