Definition of "mercurial" in English

noun

1. (obsolete) Any of the plants known as mercury, especially the annual mercury or French mercury (Mercurialis annua).

2. (astrology) A person born under the influence of the planet Mercury; hence, a person having an eloquent, quickwitted, furtive, or volatile character.

3. (chemistry) A chemical compound containing mercury.

4. (pharmacology, historical) A preparation of mercury, especially as a treatment for syphilis.

adjective

1. (comparable) Having a lively or volatile character; animated, changeable, quick-witted.

   • his mercurial temperament

2. (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).

3. (not comparable, astronomy) Pertaining to the planet Mercury.

4. (not comparable, chemistry) Of or pertaining to the element mercury or quicksilver; containing mercury.

5. (not comparable, medicine) Caused by the action of mercury or a mercury compound.

6. (not comparable, Roman mythology) Pertaining to Mercury, the Roman god of, among other things, commerce, financial gain, communication, and thieves and trickery; hence (comparable), money-making; crafty.

   • Near-synonym: Hermesian