mercurial

/mərˈkjʊriəl/
adjective
  1. Changing suddenly and often; unpredictable in mood or behavior.
    • Her mercurial temperament made it hard to know how she would react.
    • He had a mercurial personality, cheerful one moment and angry the next.
    • The stock market is mercurial, rising and falling without warning.
  2. Relating to or containing the element mercury.
    • The chemist studied mercurial solutions in the lab.
    • The old thermometer contained mercurial liquid.
    • Mercurial compounds are toxic and must be disposed of carefully.
  3. Lively, quick, and clever in thought or movement.
    • His mercurial mind jumped from one idea to the next.
    • The dancer's mercurial movements amazed the audience.
    • She had a mercurial wit that kept everyone laughing.
noun
  1. A drug or preparation containing mercury, formerly used in medicine.
    • The patient was given a mercurial to treat the infection.
    • Doctors in the 1800s sometimes prescribed mercurials for syphilis.
    • Mercurials are rarely used today because of their toxicity.
What does "mercurial" mean? | whatsthatwordmean | whatsthatwordmean