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
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.
“You don’t want to be subject to the whims of mercurial leadership where there’s all these feuds.”
From The Wall Street Journal ● Sep. 15, 2026
Cherki made his impact under Guardiola last season, although there was always a feeling the mercurial signing from Lyon for a bargain £30m could produce more.
From BBC ● Aug. 28, 2026
But ties have hit a rocky patch despite attempts to woo the mercurial US leader.
From Barron's ● Jul. 19, 2026
It’s just the latest sign that the launch of a whole ecosystem of ETFs has done little to buttress bitcoin against the whims of mercurial investors.
From MarketWatch ● Jun. 30, 2026
Kendra relished being part of the mercurial procession, overjoyed at the fortunate ending to the terrible night.
From "Fablehaven" by Brandon Mull
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Get a wordDefinitions 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.
