mercurial

1 of 2

adjective

mer·​cu·​ri·​al (ˌ)mər-ˈkyu̇r-ē-əl 

1

: of, relating to, or born under the planet Mercury

2

: having qualities of eloquence, ingenuity, or thievishness attributed to the god Mercury or to the influence of the planet Mercury

3

: characterized by rapid and unpredictable changeableness of mood

a mercurial temper

4

: of, relating to, containing, or caused by mercury

mercurially

(ˌ)mər-ˈkyu̇r-ē-ə-lē 

adverb

mercurialness noun

mercurial

2 of 2

noun

: a pharmaceutical or chemical containing mercury

Did you know?

The Roman god Mercury was the messenger and herald of the gods and also the god of merchants and thieves (his counterpart in Greek mythology is Hermes). He was noted for his eloquence, swiftness, and cunning, and the Romans named what appeared to them to be the fastest-moving planet in his honor. Mercurial comes from the Latin adjective mercurialis, meaning "of or relating to Mercury."

Synonyms

Adjective

• capricious
• changeable
• changeful
• fickle
• flickery
• fluctuating
• fluid
• inconsistent
• inconstant
• mutable
• skittish
• temperamental
• uncertain
• unpredictable
• unsettled
• unstable
• unsteady
• variable
• volatile

Choose the Right Synonym for mercurial

inconstant, fickle, capricious, mercurial, unstable mean lacking firmness or steadiness (as in purpose or devotion).

inconstant implies an incapacity for steadiness and an inherent tendency to change.

an inconstant friend

fickle suggests unreliability because of perverse changeability and incapacity for steadfastness.

performers discover how fickle fans can be

capricious suggests motivation by sudden whim or fancy and stresses unpredictability.

an utterly capricious critic

mercurial implies a rapid changeability in mood.

made anxious by her boss's mercurial temperament

unstable implies an incapacity for remaining in a fixed position or steady course and applies especially to a lack of emotional balance.

too unstable to hold a job

Examples of mercurial in a Sentence

Adjective

Few moments in English history have been more hungry for the future, its mercurial possibilities and its hope of richness, than the spring of 1603. —Adam Nicolson, God's Secretaries, 2003

Though you could see all three places in one day, each of them makes you want to stay or to keep returning to watch the effects of the changing weather and the mercurial Sicilian light. —Francine Prose, Atlantic, December 2002

Some scientists suggest that because manic-depressive patients are ever riding the bio-chemical express between emotional extremes, their brains end up more complexly wired and remain more persistently plastic than do the brains of less mercurial sorts. —Natalie Angier, New York Times, 12 Oct. 1993

Still grinning, still miming, he samba-ed across the floor … and started in on the dishes with a vigor that would have prostrated his mercurial cousin. —T. Coraghessan Boyle, Harper's, October 1987

the boss's mood is so mercurial that we never know how he's going to react to anything

Recent Examples on the Web

Adjective

Since Mercury began its retrograde journey in Sagittarius on Nov. 25, things have been in flux, particularly mercurial themes such as communication, logistics and dynamics within your immediate environment. —Valerie Mesa, People.com, 15 Dec. 2024

And Musk, once a supporter of President Obama before moving to the right in recent years, is famously mercurial. —Thomas Beaumont, Los Angeles Times, 10 Dec. 2024

Noun

LuPone portrays Rosie Morsch, Marian Henry’s (McTeer) mercurial and disapproving sister. —Denise Petski, Deadline, 22 Nov. 2024

Austin Butler is the wild-at-heart troublemaker, Jodie Comer is his worried girlfriend, but Tom Hardy shines as the bikers' mercurial, Brando-esque leader. —Brian Truitt, USA TODAY, 16 Aug. 2024

Word History

Etymology

Adjective

see mercury

Noun

see mercury

First Known Use

Adjective

14th century, in the meaning defined at sense 1

Noun

1676, in the meaning defined above

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Kids Definition

mercurial

adjective

mer·​cu·​ri·​al

(ˌ)mər-ˈkyu̇r-ē-əl

1

: characterized by rapid and unpredictable change of mood

2

: mercuric

mercurially

-ē-ə-lē

adverb

Medical Definition

mercurial

1 of 2 adjective

mer·​cu·​ri·​al (ˌ)mər-ˈkyu̇r-ē-əl 

: of, relating to, containing, or caused by mercury

mercurial salves

mercurial

2 of 2 noun

: a pharmaceutical or chemical containing mercury

the diuretic action of mercurials