Definitions

mercurial

[mer-kyoor-ee-uhl] / mərˈkyʊər i əl /

ADJECTIVE

flighty, temperamental

Synonyms

STRONGEST

changeable effervescent erratic impulsive resilient unpredictable volatile

WEAK

blowing hot and cold bubbleheaded buoyant capricious elastic expansive fickle flaky flip fluctuating gaga gay inconstant irregular irrepressible lighthearted lively lubricious mad mobile movable quicksilver spirited sprightly ticklish unstable up-and-down variable yo-yo

Antonyms

STRONGEST

certain constant predictable reliable stable steady sure unchanging

WEAK

calm tranquil unchangeable unperturbable unvarying

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.

But it will have its work cut out to placate the mercurial Republican.

From Barron's • Apr. 28, 2026

Gorka can be remarkably candid and mercurial for a senior official with such a sensitive remit, according to hours of his public remarks reviewed by ProPublica.

From Salon • Apr. 22, 2026

They are, instead, lacunas to be reckoned with, stemming from the abiding obscurity of human psychology and deepened by the mercurial, ever-fading state of memory.

From The Wall Street Journal • Apr. 16, 2026

Chelsea's Cole Palmer showed his quality with a goal in the Euro 2024 final in Berlin and has the sort of mercurial talent that could give England an X-factor in the World Cup.

From BBC • Apr. 1, 2026

A battle raged between two titans: the professor Booker T. Washington and the brilliant, mercurial, and quarrelsome W. E. B. Du Bois.

From "The Best of Enemies" by Osha Gray Davidson

Vocabulary lists containing mercurial

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