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

Master of the trivela, lover of a rabona - mercurial and erratic, but show-stoppingly skilful.

From BBC • Mar. 24, 2026

As Cassio, both Jake Roxander and Andrew Robare were notably cocky and mercurial.

From The Wall Street Journal • Mar. 18, 2026

“Once in a while Lainie suggests that we follow it around ourselves but I think that would only be a temporary solution, we are too mercurial for our own good.”

From "The Night Circus" by Erin Morgenstern

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