from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Roman Mythology Of or relating to the god Mercury.
  • adj. Astronomy Of or relating to the planet Mercury.
  • adj. Having the characteristics of eloquence, shrewdness, swiftness, and thievishness attributed to the god Mercury.
  • adj. Containing or caused by the action of the element mercury.
  • adj. Quick and changeable in temperament; volatile: a mercurial nature.
  • n. A pharmacological or chemical preparation containing mercury.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Volatile; erratic; unstable; flighty; fickle or changeable in temperament.
  • adj. Lively; clever; sprightly; animated; quick-witted.
  • adj. Of, or pertaining to the element mercury; containing mercury; caused by the action of mercury or quicksilver.
  • adj. Having characteristics attributed to the Roman god Mercury, such as swiftness, eloquence, shrewdness, and thievishness.
  • adj. (often capitalized, see Mercurial) Of or pertaining to the Roman god Mercury.
  • adj. (often capitalized, see Mercurial) Of or pertaining to the planet Mercury; under the supposed astrological influence of the planet Mercury.
  • n. A chemical containing mercury.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Having the qualities fabled to belong to the god Mercury; swift; active; sprightly; fickle; volatile; changeable
  • adj. Having the form or image of Mercury; -- applied to ancient guideposts.
  • adj. Of or pertaining to Mercury as the god of trade; hence, money-making; crafty.
  • adj. Of or pertaining to, or containing, mercury. See Mercury, 2.
  • adj. Caused by the use of mercury.
  • n. A person having mercurial qualities.
  • n. A preparation containing mercury.

from The Century Dictionary and Cyclopedia

  • [capitalized] Pertaining to the god Mercury; having the form or qualities attributed to Mercury.
  • Like Mercury in character; having the moral or mental qualities ascribed to the god Mercury, or supposed by astrologists to belong to those under his star, the planet Mercury; light-hearted; gay; active; sprightly; flighty; fickle; changeable; volatile.
  • Pertaining to Mercury as god of trade; hence, pertaining to trade or money-making: as, mercurial pursuits.
  • Pertaining to Mercury as herald; hence, giving intelligence; pointing out; directing.
  • Pertaining or relating to mercury or quicksilver.
  • n. A person possessing any of the attributes of the god Mercury; one of mercurial temperament; a sprightly person; also, one given to trickery; a cheat or thief.
  • n. A preparation of mercury used as a drug.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. relating to or under the (astrological) influence of the planet Mercury
  • adj. liable to sudden unpredictable change
  • adj. relating to or containing or caused by mercury
  • adj. relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English, of the planet Mercury, from Latin mercuriālis, of the god or planet Mercury, from Mercurius, Mercury.


  • I guess the "mercurial" is a pretty negative thing.

    Kittenpie Pondering

  • Jobs is often described as mercurial and prone to outbursts, while Cook, who was raised in a small town in Alabama, is polite and soft-spoken, The Times reports.

    Breaking News: CBS News

  • A number of people have described Denny as "mercurial" - the commanding personality who was sometimes afraid to go onstage.

    NPR Topics: News

  • Carlos Zambrano -- who almost defines the term "mercurial" -- can put his head in the game tonight long enough to beat a tough pitcher in Braves made bigger news than their loss last night; just a couple of days after I asked Martin at the Braves released him.

    Bleed Cubbie Blue

  • Brown has been described as mercurial, even erratic.

    Jerry Brown's Long and Winding Road

  • He's best described as a mercurial person, so there's a chance he might yet change his mind -- selfishly, I hope he does -- but his decision is consistent with the person he is and was and always will be.

    Joaquin Phoenix Retires

  • As a businesswoman, she was called mercurial, cunning, cynical, and calculating, but personally she was softhearted and had a passion for helping the less fortunate who called her “the Angel of the West”.


  • He's best described as a mercurial person, so there's a chance he might yet ...

    James Gray: Joaquin Phoenix Retires

  • McCain is described as mercurial and adversarial; he has become notorious for his temper tantrums and many believe he suffers from untreated Post Traumatic Stress Disorder resulting from his six years as a P.O.W. Despite these marked personal differences, the starkest contrast between Obama and McCain is in their worldviews.

    Obama-McCain: Lincoln vs. Rambo

  • He was very often described as mercurial, difficult to work with.

    CNN Transcript Jan 22, 2006


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  • (of a person) prone to unexpected and unpredictable changes in mood

    The fact that Ella’s moods were as mercurial as the weather was problematic for her relationships—it didn’t help that she lived in Chicago

    October 1, 2016

  • Just how menopausal is peri-menopausal, then?

    July 12, 2008

  • It also, apparently, is used to describe a peri-menopausal woman... or so I've heard.

    July 11, 2008

  • This word was used a lot to describe me at about seven years old.

    July 10, 2008

  • Oh, it is for Mercury.

    Mercutio was named because he is mercurial. Interesting what a missing comma can do.

    November 18, 2007

  • I assumed it was after Mercury!

    November 18, 2007

  • To be up and down like Mercutio.

    November 17, 2007

  • "A dark mercurialised face appears, leading a veiled figure."

    Joyce. Ulysses, 15

    February 5, 2007