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.

President Donald Trump has a notably mercurial personality.

From BBC • Apr. 28, 2026

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

As Simon Elliott describes in his biography “The African Emperor,” Severus was a mercurial and contradictory character, capable by turns of savagery, cunning, wit and generosity, and always blessed with a sense of the theatrical.

From The Wall Street Journal • Mar. 19, 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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