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
- mercuriality noun
- mercurially adverb
- mercurialness noun
- unmercurial adjective
- unmercurially adverb
- unmercurialness noun
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.
In recent years, the mercurial superstar has faced a number of public and legal dramas.
From Los Angeles Times • Mar. 11, 2026
While they have lost mercurial full-back Ange Capuozzo to injury, centre Ignacio Brex has returned to the set-up after missing the past two games for personal reasons.
From BBC • Mar. 3, 2026
Mr. McCallum’s sharp alliterations and choice of words transform a book review into a wonderful exploration of a mercurial star.
From The Wall Street Journal • Mar. 2, 2026
Capital Group ascended to the No. 1 spot by taking advantage of mercurial markets and seeing long-term bets pay off.
From Barron's • Feb. 26, 2026
He was in a mercurial Hastings temper, and a halter and chain looped over his bridle barely restrained him.
From "Seabiscuit: An American Legend" by Laura Hillenbrand
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.
