Synonyms of mercurial

mercurial

adjective

(ˌ)mər-ˈkyu̇r-ē-əl 

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

Synonyms & Similar Words

• volatile
• unpredictable
• unstable
• changeful
• inconsistent
• variable
• temperamental
• fickle
• uncertain
• capricious
• mutable
• unsettled
• inconstant
• fluctuating
• changeable
• erratic
• fluid
• skittish
• up in the air
• unsteady
• flickery
• random
• unreliable
• arbitrary
• haphazard
• ambivalent
• scattered
• aimless
• desultory
• shaky
• stray
• protean
• untrustworthy
• slapdash
• hit-or-miss
• undependable
• vacillating
• dicey
• wavering
• versatile
• adaptable
• irregular
• mobile
• shilly-shallying
• hesitating
• shilly-shally

Antonyms & Near Antonyms

• constant
• certain
• stable
• immutable
• steady
• predictable
• stationary
• unchanging
• invariable
• unchangeable
• uniform
• settled
• persistent
• permanent
• even
• unvarying
• changeless
• durable
• equable
• reliable
• lasting
• abiding
• dependable
• true
• trustworthy
• sure
• trusty
• tried
• tried-and-true

Synonym Chooser

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

Recent Examples of mercurial

The war on drugs was the signature campaign platform that swept the mercurial Duterte to power in 2016. —Reuters, NBC News, 12 Mar. 2025

The shed manufacturers were a kernel of the idea that stuck: small homes, built in a factory, not out on a site where the mercurial Oklahoma weather could cause expensive delays. —Andrea Riquier, USA TODAY, 9 Mar. 2025

Themes pick and unpick themselves as neurotically as László Tóth (Adrien Brody) sketches out designs for a community center at the behest of his mercurial patron (Guy Pearce), but Blumberg also constructs a musical journey between characters and across decades with his music. —Sarah Shachat, IndieWire, 12 Feb. 2025

Yes, the final seasons were somewhat patchy, but the first two are almost flawless, spearheaded by a stoic Claire Foy alongside Matt Smith’s mercurial Prince Philip and Vanessa Kirby’s devastatingly glamorous Princess Margaret. —Radhika Seth, Vogue, 9 Feb. 2025