Definition of mercurial in US English:



  • 1(of a person) subject to sudden or unpredictable changes of mood or mind.

    ‘his mercurial temperament’
    • ‘He grinned briefly in a mercurial change of mood.’
    • ‘Okada projected the mercurial shift of moods in Beethoven's Fantasie Op 77 with resonant sonority.’
    • ‘He then embarked upon a legal career which was characterised by often brilliant legal exposition, and mercurial temperament.’
    • ‘He had a mercurial temperament and was never one to hold back his views, even in the face of opposition.’
    • ‘In a mercurial change of temper, he grabbed her shoulders and shook her, once, twice.’
    • ‘During his four years in office, Mr. Chen has proven to be a mercurial and unpredictable leader.’
    • ‘The mercurial singer-songwriter's mood is as unpredictable as Halifax weather and each night's performance lives and dies on which attitude the capricious star brings to the rink.’
    • ‘At times you feel frustrated with Ellie and her mercurial temperament.’
    • ‘One of the most talented and versatile Scottish performers, McKidd is mesmerising as Frankie, capturing all the mercurial moods of a man who can switch from sentimentality to aggression at the flick of a switchblade.’
    • ‘Jim's mind is mercurial, but I like his company more than anything.’
    • ‘Ms Short is notorious for her outspoken comments and her mercurial temperament.’
    • ‘Rhea's temperament was infamously mercurial - one would never know what she was thinking, or when she might strike.’
    • ‘Nor does she depict adolescence as a period of mental instability, characterized by mercurial moods and impulsive, self-gratifying actions.’
    • ‘No decision of importance could be made without the chairman, and he was mercurial, often changing his mind once a decision had been made.’
    • ‘Could it be my mercurial temper, causing many rash actions or hurtful, wicked comments?’
    • ‘Regardless of her mercurial mood, he always managed to stay gentle with her.’
    • ‘He is mercurial, unpredictable and headstrong.’
    • ‘Their awkwardness, overextended maturity, mercurial temperaments, and easy companionship were all spot on.’
    • ‘To blow off those dear friends who've put up with your mercurial moods for long is just plain cruel and thoughtless, so start returning those calls and those emails.’
    • ‘Mrs. Lincoln became known as much for her fashion sense as her mercurial temperament and place in history.’
    volatile, capricious, temperamental, excitable, fickle, changeable, unpredictable, variable, protean, mutable, erratic, quicksilver, inconstant, inconsistent, unstable, unsteady, fluctuating, ever-changing, kaleidoscopic, fluid, wavering, vacillating, moody, flighty, wayward, whimsical, giddy, impulsive
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    1. 1.1 (of a person) sprightly; lively.
      • ‘He's always been a mercurial musician with one foot on his distortion pedal and one foot out the door on the way to his next project.’
      • ‘He didn't have the polish and professionalism that would define the CBS era, but he wasn't quite the mercurial genius our lazy memories would have us believe, either.’
      • ‘A mature woman with an in form, solid basic game against a young brilliant, mercurial player lacking in confidence.’
      • ‘‘You have the most mercurial personality I have ever met,’ he stated.’
      • ‘They require complex and varied solutions, involving complicated, multiplex, mercurial people who use a wide variety of approaches.’
  • 2Of or containing the element mercury.

    • ‘The condensation beading on it gave it a mercurial sheen.’
    • ‘Over the years, researchers provided Eli Lilly with numerous articles indicating the hazards of injecting humans with mercurial substances such as thimerosal.’
    • ‘This research is an effort to create an awareness. of the potential hazards of some Chinese patent medicines which contain mercurial ingredients.’
    • ‘These mercurial chemicals are never taken lightly.’
    • ‘Everyone is wise to the mercury dangers in paints, but patients need to know that button batteries, mercurial antiseptics and broken thermometers are sources of mercury.’
    • ‘Brownish-black may indicate chronic mercurial poisoning caused by the formation of sulfide of mercury in the tissues.’
    • ‘The mercurial bromide was re-extracted and analyzed by capillary gas chromatography/electron capture detector, using an internal standard for quantification.’
    • ‘In acute LV failure with pulmonary edema, phlebotomy, rotating tourniquets, and parenteral mercurial diuretics were effective.’
    • ‘To determine the extent to which mercury-sensitive water channels are involved in the control of root water flow, mercurial inhibition of root water flow was also examined using a pressure-flux approach.’
    • ‘I shuffled off to where he'd pointed, feeling a cold bar of mercurial metal, like in thermometers, stretch from the first bone of my chest, and settling into the pit of my stomach.’
    • ‘And don't forget ‘liquid metal,’ dynamically controlled mercurial globs you can push around on your canvas.’
    • ‘Mercury amalgams are used in dentistry, and mercurial aids such as the thermometer and blood pressure apparatus aid the doctor.’
  • 3Of the planet Mercury.

    • ‘Modern authors also note the Mercurial influence.’
    • ‘The agate stones have a very earthy, grounding influence, which can be invaluable to the Mercurial personality.’
    • ‘Every person, by his own astrological make up will have a Mercurial connection with the transpersonal plants, either by aspect or sign rulership.’
    • ‘I'm not saying those turning points are punctuated by Mercurial storms like I was some Greek hero or something.’
    • ‘The odour of Mercurial herbs is described as ‘highly subtle and penetrating, refreshing to the heart and brain.’’
    • ‘The Ascendant to quintile Mercury suggests that he ‘should now have rectified his books of accounts and receive much benefit from Mercurial men’.’
    • ‘Tejat and Dirah are both located in the left foot of Pollux, so traditionally share the Mercurial / Venus nature.’
    • ‘Uranian mind-vibes can sometimes get Mercurial Virgos overwrought and on edge.’
    • ‘As for Venus, the dates of Mercurial transits are spaced by six months: they all fall within a few days of May 8 and November 10.’


usually mercurials
  • A drug or other compound containing mercury.

    • ‘In rice seedlings, the application of mercurials had an effect on whole plant conductance only when plants were water stressed by the presence of polyethylene glycol, but not in control growth conditions.’
    • ‘Results from experiments with mercurials must be viewed with caution because mercury also blocks the pores of other transmembrane proteins, some of which are involved in ion transport.’
    • ‘Before the cancellation of the volatile mercurials, fungicides for treating seed were generally classified as volatile and non-volatile.’
    • ‘None of the subjects had a history of occupational exposure to Hg and mercurials, symptoms resulting from disorders of the digestive system, amalgam fillings, or experienced digestive-system surgery.’
    • ‘Inhibition of water flow by mercurials in membrane vesicles, individual root cells and whole root systems points to the importance of aquaporins in the regulation of water flow through root systems.’
    • ‘Special multiwall or tightly woven bags are recommended for seed that has been treated with mercurials or similarly toxic substances.’
    • ‘A few attempts have been made to demonstrate the action of water channels in roots such as by closing them with mercurials.’
    • ‘In refractory HF with anasarca, hyperchloremic acidosis was induced to potentiate the effect of intravenous mercurials.’


Late Middle English (in mercurial (sense 3 of the adjective)): from Latin mercurialis ‘relating to the god Mercury’, from Mercurius ‘Mercury’. mercurial (sense 1 of the adjective) dates from the mid 17th century.