mercurial
Americanadjective
-
changeable; volatile; fickle; flighty; erratic.
a mercurial nature.
- Synonyms:
- indecisive, inconstant
-
animated; lively; sprightly; quick-witted.
- Synonyms:
- spirited
- Antonyms:
- phlegmatic
-
pertaining to, containing, or caused by the metal mercury.
-
(initial capital letter) of or relating to the god Mercury.
-
(initial capital letter) of or relating to the planet Mercury.
noun
adjective
-
of, like, containing, or relating to mercury
-
volatile; lively
a mercurial temperament
-
(sometimes capital) of, like, or relating to the god or the planet Mercury
noun
Other Word Forms
Derived Forms
Etymology
Origin of mercurial
First recorded in 1350–1400; Middle English, from Latin mercuriālis “of or pertaining to the god or planet Mercury”; see origin at mercury, -al 1
Explanation
Mercurial describes someone whose mood or behavior is changeable and unpredictable, or someone who is clever, lively, and quick. With a mercurial teacher, you never know where you stand. Mercury was the ancient Roman god of commerce and messenger of the gods, and the planet Mercury was named after the Roman god. In Middle English, this adjective meant "relating to the planet or god Mercury" and derives from Latin mercuriālis, from Mercurius "Mercury." A mercurial personality has the unpredictability associated with the god Mercury or, in astrology, is supposedly influenced by the planet.
Vocabulary lists containing mercurial
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Mercurial and unreliable in the studio, Stewart would sometimes fall asleep on the couch during recording sessions or lie down in the vocal booth.
From The Wall Street Journal • Mar. 27, 2026
The haircut, the silver-and-lime Mercurial Vapors, a poacher with a toe-poke.
From BBC • Mar. 3, 2026
Mercurial running back Najee Harris has struggles at times to put into words his frustration with the direction of the offense following losses.
From Seattle Times • Nov. 29, 2023
Nike has also doubled down on its product lines such as the LeBron 20s and Nike Mercurial shoes, while also grabbing a bigger chunk of the growing China market.
From Reuters • Mar. 20, 2023
Negretti & Zambra’s Second Patent Mercurial Minimum Thermometer.—In this thermometer a principle is used that has been long known to scientific men, viz. the affinity of mercury for platinum.
From A Treatise on Meteorological Instruments Explanatory of Their Scientific Principles, Method of Construction, and Practical Utility by Negretti, Henry
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
