Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

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

from The Century Dictionary.

  • [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.
  • noun 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.
  • noun A preparation of mercury used as a drug.

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

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

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

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

Etymologies

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.]

Examples

  • 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

  • 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

  • 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.

    William Bradley: Jerry Brown's Long and Winding Road

  • 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

  • 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.

    James Gray: Joaquin Phoenix Retires

Comments

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

    Joyce. Ulysses, 15

    February 5, 2007

  • To be up and down like Mercutio.

    November 17, 2007

  • I assumed it was after Mercury!

    November 18, 2007

  • Oh, it is for Mercury.

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

    November 18, 2007

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

    July 10, 2008

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

    July 11, 2008

  • Just how menopausal is peri-menopausal, then?

    July 12, 2008

  • (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