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

Because of Butler’s mercurial behavior and history of torching relationships, Riley should have found Butler in May or June, pressed him for a straight answer, and traded him quietly if Butler had leveled with him. —Barry Jackson, Miami Herald, 25 Mar. 2025

No longer the beloved Renaissance prince of his youth, Henry was, by his mid-40s, an increasingly infirm and mercurial monarch who had few qualms about sending his closest companions—among them the aforementioned Thomas More—to the executioner’s block. —Meilan Solly, Smithsonian Magazine, 20 Mar. 2025

Like Jackson, Solomon has a mercurial, aspiring politician of a son, Junior (Glenn Davis), who, in the timeline of Purpose, is just out of a prison term for tax fraud, and whose wife, Morgan (Alana Arenas), is about to go in and serve her time. —Jackson McHenry, Vulture, 17 Mar. 2025

Among the topics discussed: The Nuggets are in the middle of a mercurial stretch of basketball that’s included some of their best (Nikola Jokic’s 30-20-20 vs. Phoenix) and worst (Wizards loss) games of the season. —Aaron Ontiveroz, The Denver Post, 18 Mar. 2025