mercury

noun

mer·​cu·​ry ˈmər-kyə-rē 

-k(ə-)rē

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

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

Atlantic mackerel is very low in mercury and is a healthy seafood option.14 10. —Jillian Kubala, Health, 19 May 2025

Overall, the levels of total heavy metals, including cadmium, lead and mercury, ranged, on average, from 63 ppb to 188 pbb among the rice samples — though some samples exceeded 240 ppb, for example. —Jordan Freiman, CBS News, 15 May 2025

Those byproducts—and heavy metals like lead, mercury, cadmium and chrome—can remain in the environment after serving their industrial purposes, contaminating soil and posing a threat to both environmental and human health. —Lauren Oster, Smithsonian Magazine, 12 May 2025

Bluefin tuna also tends to be high in mercury, but the levels depend on where they are caught. —Nancy Lebrun, Verywell Health, 8 May 2025

Word History

Etymology

Latin Mercurius, Roman god and the planet

First Known Use

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

Phrases Containing mercury

• bichloride of mercury
• mercury chloride
• mercury-vapor lamp

Rhymes for mercury

• methylmercury

Kids Definition

mercury

noun

mer·​cu·​ry ˈmər-kyə-rē 

-k(ə-)rē

1

a

: a heavy silver-white poisonous metallic element that is liquid at ordinary temperatures

called also quicksilver

see element

b

: the column of mercury in a formerly common type of thermometer or barometer

2

capitalized : the planet nearest the sun see planet

Medical Definition

mercury

noun

mer·​cu·​ry ˈmər-kyə-rē, -k(ə-)rē 

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