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The annual mercury (Mercurialis annua), one of the varieties of mercurial (noun sense 1)
A sample of a mercurial (noun sense 3), in this case a compound with the molecular formula Ag2HgI4
An 18th-century jar used for storing mercurials (noun sense 4) in the form of pills[n 1]

Noun sense 1 (“(obsolete) plant known as mercury”) is from Middle English mercurial, mercuryal (a plant, probably the goosefoot (Chenopodium); (possibly) dog's mercury (Mercurialis perennis)),[1] from Anglo-Norman mercurial and Old French mercurial, or directly from their etymon Latin mercuriālis (a plant, probably annual mercury (Mercurialis annua)), from mercuriālis (pertaining to the Roman god Mercury, adjective), from Mercurius (the Roman god Mercury) + -ālis (suffix forming adjectives of relationship from nouns).[2]

Later adjective and noun uses may have been directly derived from Latin mercuriālis (adjective),[2] whence Middle English mercurial, Mercurial (under the astrological influence of the planet Mercury).[3]



mercurial (plural mercurials)

  1. (obsolete) Any of the plants known as mercury, especially the annual mercury or French mercury (Mercurialis annua). [13th–17th c.]
  2. (astrology) A person born under the influence of the planet Mercury. [from 16th c.]
  3. (chemistry) A chemical compound containing mercury.
  4. (medicine, historical) A preparation of mercury, especially as a treatment for syphilis. [from 17th c.]
    • 1858, James Copland, “POISONS—Poisoning—Poisoned—Symptoms and Treatment of”, in A Dictionary of Practical Medicine. [] In Three Volumes, volume III, part I, London: Longman, Brown, Green, Longmans, & Roberts, OCLC 934279265, paragraph 580, pages 413–414:
      [A] small dose of the mercurial may cause excessive salivation; and, if this discharge be attended by much soreness of throat, it is most difficult to determine whether the salivation is actually the result of the mercurial, or merely symptomatic of the sore throat and cold. If it proceed from the mercurial, there will generally be some tenderness of the gums, a soft and flabby state of the sides of the tongue, and it will generally be more obstinate.


mercurial (comparative more mercurial, superlative most mercurial)

  1. (comparable) Having a lively or volatile character; animated, changeable, quick-witted. [from 17th c.]
    Synonyms: fickle, unpredictable
    his mercurial temperament
    • 1649, Jacob Behmen [i.e., Jakob Böhme], “The Nineteenth Epistle”, in J[ohn] E[llistone], transl., The Epistles of Jacob Behmen: Aliter, Tevtonicvs Philosophvs. [] Translated out of the German Language, London: Printed by Matthew Simmons [], OCLC 61214739, paragraph 24, page 149:
      When the ſoule bringeth its fire deſire out of its owne ſelfe-will into the Love-deſire of God; and goeth out of its owne ſelfneſſe, and ſinketh into the mercy and compaſſion of God, and caſteth it ſelfe into the death of Chriſt; and willeth no longer the fire-ſource, but deſireth in its fire-life to be dead in the death of Chriſt; then the poyſon of the Mercuriall life dyeth in the will of iniquity, and there ariſeth a new twigge, and budding of love-deſire.
    • 1723, Charles Walker, “Of Her Birth, Education, and First Setting Out in the World”, in Authentick Memoirs of the Life Intrigues and Adventures of the Celebrated Sally Salisbury. [], London: [s.n.], OCLC 519787262, pages 11–12:
      From the natural Mercurial Briskneſs of her [Sally Salisbury's] Temper, a ſedentary Life had ever been her Averſion, wherefore ſhe rather choſe to follow the Fortunes of a Wheel-Barrow, than thoſe of a Diſtaff; []
    • 2016 October 22, Rami G[eorge] Khouri, “Lebanese Oligarchy Preserves Its Interests Once Again”, in Al Jazeera[1], archived from the original on 1 August 2018:
      Lebanon has shown once again that it is a land of dazzling deals and mercurial personalities, including in the realm of the national presidency itself.
  2. (not comparable, Ancient Rome, religion) Pertaining to Mercury, the Roman god of, among other things, commerce, financial gain, communication, and thieves and trickery; hence (comparable), money-making; crafty. [from 15th c.]
  3. (not comparable, astrology) Pertaining to the astrological influence of the planet Mercury; having the characteristics of a person under such influence (see adjective sense 1). [from 16th c.]
    • 1682, Joseph Blagrave, “[The Effects of Directions.] The Sun Directed unto Promittors.”, in Obadiah Blagrave, editor, Blagrave’s Introduction to Astrology. In Three Parts. [], London: Printed by E. Tyler, and R. Holt, for Obadiah Blagrave, [], OCLC 228724142, part III, page 254:
      The Sun to the Terms of Mercury. It inclineth the native to be Mercurial, given to ſtudy Arts and Sciences, and to delight in reading, and to follow his Calling with chearfulneſs.
    • 1852, William Lilly; Zadkiel [pseudonym; Richard James Morrison], “Of the Ninth House and Its Questions. Long Journeys, Voyages, Arts, Science, Church Preferment, Law, &c.”, in An Introduction to Astrology []: A Grammar of Astrology, and Tables for Calculating Nativities. [], London: H[enry] G[eorge] Bohn, [], OCLC 1077929409, page 268:
      6thly, The ☽ separates from a △ of ♂︎, and applies to ☍ of ☿, lord of the 3d; which intimated that some neighbour of the querent, either with a letter, words, or cross information, would wholly destroy the querent's hopes; and that mercurial men, viz. scholars or divines, would be his enemies: []
  4. (not comparable, astronomy) Pertaining to the planet Mercury. [from 14th c.]
  5. (not comparable, chemistry) Of or pertaining to the element mercury or quicksilver; containing mercury. [from 16th c.]
    • 1617, John Woodall, “Of the Small Siringe”, in The Svrgions Mate, or A Treatise Discouering Faithfully and Plainely the due Contents of the Svrgions Chest, the Uses of the Instruments, the Vertues and Operations of the Medicines, the Cures of the Most Frequent Diseases at Sea: [], London: Printed by Edward Griffin for Laurence Lisle, [], OCLC 960102874, page 22:
      Beware alſo of Mercuriall lotions, I meane any which haue Mercurie Sublimate Precipitat or otherwiſe prepared in them, for though they haue good qualities, yet they are vpon my knowledge and experience dangerous, []
    • 1734, T[homas] K[night], A Critical Dissertation upon the Manner of the Preparation of Mercurial Medicines, and Their Operation on Human Bodies; particularly Those Most in Fashion: [], London: Printed for Harmen Noorthouck [], OCLC 14332927, page 52:
      [] Dr. Francis Fuller, [] upon wearing a Quick-ſilver Girdle, for the Cure of the Itch, (and that after an inconſiderate and raſh manner) was brought under a violent Spaſmodick Diſtemper, which was ſupposed by himſelf and others to be owing to ſome Mercurial Particles lodg'd in ſome excretory Ducts of the Brain.
    • 1773, Henry Saffory, The Inefficacy of All Mercurial Preparations in the Cure of Venereal and Scorbutic Disorders, Proved from Reason and Experience, [], London: Printed for the author; and sold by T. Evans, [], and Mr. Southern, [], OCLC 81311187, pages 31–32:
      If to theſe we add the inconveniences inſeparable from mercurial preparations, and which are always the conſequences of their uſe; if we conſider the ſmall number of patients to whom mercury may be exhibited with ſafety, [] the uſe of mercurial medicines will be confined within very narrow limits.
  6. (not comparable, medicine) Caused by the action of mercury or a mercury compound.
    • 1810, Andrew Mathias, “Section II. The Exciting Causes of the Mercurial Disease.”, in The Mercurial Disease. An Inquiry into the History and Nature of the Disease Produced in the Human Constitution by the Use of Mercury, with Observations on Its Connexion with the Lues Venerea, London: Printed for Becket and Porter, []; John Murray, []; and J[oseph] Johnson and Co., [], OCLC 931351039, page 84:
      The last exciting cause of the mercurial ulcer, which I shall now mention, is the use of the knife or of the caustic, during a mercurial course, to wounds made or enlarged at this time; for the great additional irritation, which the operation must produce, disposes such wounds to take on easily the mercurial disease.

Alternative formsEdit

  • (pertaining to the Roman god Mercury or planet Mercury): Mercurial

Derived termsEdit

Related termsEdit



  1. ^ From the collection of the Wellcome Library in London, England, UK.


  1. ^ mercuriāl, n.” in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 5 May 2019.
  2. 2.0 2.1 mercurial, n. and adj.”, in OED Online  , Oxford: Oxford University Press, September 2001; “mercurial” in Lexico,; Oxford University Press.
  3. ^ Mercuriāl, adj.” in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 5 May 2019.

Further readingEdit



mercurial (not comparable)

  1. mercurial, pertaining to mercury (metal)

Middle EnglishEdit


Borrowed from Latin mercuriālis, Mercuriālis (pertaining to the Roman god Mercury).


mercurial (uncountable)

  1. (botany) A plant belonging to the genus Chenopodium; a goosefoot.
    Synonym: mercurie

Alternative formsEdit



  1. (astrology, astronomy) Pertaining to or under the influence of the planet Mercury.

Alternative formsEdit





mercurial (plural mercuriales)

  1. mercurial