MERCURIAL Synonyms: 75 Similar and Opposite Words

Q: How does the adjective 'mercurial' differ from other similar words?

Some common synonyms of mercurial are capricious , fickle , inconstant , and unstable . While all these words mean "lacking firmness or steadiness (as in purpose or devotion)," mercurial implies a rapid changeability in mood. // made anxious by her boss's mercurial temperament

Q: When could 'capricious' be used to replace 'mercurial'?

The words capricious and mercurial can be used in similar contexts, but capricious suggests motivation by sudden whim or fancy and stresses unpredictability. // an utterly capricious critic

Q: When is 'fickle' a more appropriate choice than 'mercurial'?

While in some cases nearly identical to mercurial , fickle suggests unreliability because of perverse changeability and incapacity for steadfastness. // performers discover how fickle fans can be

Q: When is it sensible to use 'inconstant' instead of 'mercurial'?

The synonyms inconstant and mercurial are sometimes interchangeable, but inconstant implies an incapacity for steadiness and an inherent tendency to change. // an inconstant friend

Q: When would 'unstable' be a good substitute for 'mercurial'?

Although the words unstable and mercurial have much in common, unstable implies an incapacity for remaining in a fixed position or steady course and applies especially to a lack of emotional balance. // too unstable to hold a job

mercurial

adjective

(ˌ)mər-ˈkyu̇r-ē-əl

Definition of mercurial

as in volatile

likely to change frequently, suddenly, or unexpectedly the boss's mood is so mercurial that we never know how he's going to react to anything

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How does the adjective mercurial differ from other similar words?

Some common synonyms of mercurial are capricious, fickle, inconstant, and unstable. While all these words mean "lacking firmness or steadiness (as in purpose or devotion)," mercurial implies a rapid changeability in mood.

made anxious by her boss's mercurial temperament

When could capricious be used to replace mercurial?

The words capricious and mercurial can be used in similar contexts, but capricious suggests motivation by sudden whim or fancy and stresses unpredictability.

an utterly capricious critic

When is fickle a more appropriate choice than mercurial?

While in some cases nearly identical to mercurial, fickle suggests unreliability because of perverse changeability and incapacity for steadfastness.

performers discover how fickle fans can be

When is it sensible to use inconstant instead of mercurial?

The synonyms inconstant and mercurial are sometimes interchangeable, but inconstant implies an incapacity for steadiness and an inherent tendency to change.

an inconstant friend

When would unstable be a good substitute for mercurial?

Although the words unstable and mercurial have much in common, unstable implies an incapacity for remaining in a fixed position or steady course and applies especially to a lack of emotional balance.

too unstable to hold a job

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of mercurial Hinduism is a narrative religion; its mercurial wisdom is lightened and sweetened by stories, softened by ambiguities, sharpened by paradoxes. — Chandrahas Choudhury, Condé Nast Traveler, 5 July 2026 But Fritz is far less mercurial and far more reliable, which counts for more than fans assume when Grand Slams get tight. — Ava Wallace, New York Times, 5 July 2026 America, the world’s oldest, continuous, modern democracy, will soon celebrate its 250th birthday—mired in conflict and piloted by a belligerent and mercurial nationalist. — Dominic Erdozain, Time, 3 July 2026 Compared with mercurial stocks, real estate feels like a stable investment. — Daniel De Visé, USA Today, 30 June 2026 See All Example Sentences for mercurial

Recent Examples of Synonyms for mercurial

Adjective

The South Korean benchmark now hovers at around 6,700, having experienced volatile swings due to the heavy dependence on heavyweights Samsung Electronics and SK Hynix.

— Lim Hui Jie, CNBC, 24 July 2026
As a politician of some experience, she is presumably unfazed by the sorts of challenges that come with governing a volatile section of her volatile country.

— Kevin Sieff, The Atlantic, 24 July 2026

Definition of volatile

Adjective

These maps account for a range of variables, including cargo-shipping routes, surface currents, wind patterns, and the unpredictable drift of objects at sea.

— Alexander Klose, Scientific American, 24 July 2026
Much of Crown Center is indoors or covered, which is a big plus for when weather becomes unpredictable.

— Taylor Haught, Kansas City Star, 24 July 2026

Definition of unpredictable

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“Mercurial.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/mercurial. Accessed 31 Jul. 2026.

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Synonyms of mercurial

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