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.

Your first chance to see whether mercurial French forward Kylian Mbappé, the world’s best player, is paying full attention this year.

From Salon • Jun. 11, 2026

President Donald Trump has a notably mercurial personality.

From BBC • Apr. 28, 2026

Such uncertainty is the main enticement of this small, mercurial book.

From The Wall Street Journal • Mar. 31, 2026

The mercurial striker last played for his country in October 2023.

From Barron's • Mar. 31, 2026

Under the punishment inflicted by the Council his mercurial spirit had fallen low and he had become the apathetic wretch the sight of whom had so much shocked Bigwig.

From "Watership Down: A Novel" by Richard Adams

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