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.

Mercurial and unreliable in the studio, Stewart would sometimes fall asleep on the couch during recording sessions or lie down in the vocal booth.

From The Wall Street Journal • Mar. 27, 2026

The haircut, the silver-and-lime Mercurial Vapors, a poacher with a toe-poke.

From BBC • Mar. 3, 2026

Mercurial boxer Ryan Garcia caught a break Tuesday when a judge dismissed a misdemeanor vandalism charge against him over the objections of the Los Angeles County district attorney’s office.

From Los Angeles Times • Oct. 9, 2024

Mercurial running back Najee Harris has struggles at times to put into words his frustration with the direction of the offense following losses.

From Seattle Times • Nov. 29, 2023

Mercurial disinfecting solutions or salves must be used cautiously.

From Special Report on Diseases of Cattle by United States. Bureau of Animal Industry

Vocabulary lists containing mercurial

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