¹mercurial

adjective mer·cu·ri·al \(ˌ)mər-ˈkyu̇r-ē-əl\

: changing moods quickly and often

: changing often : very changeable

: very lively and quick

Full Definition of MERCURIAL

: of, relating to, or born under the planet Mercury

: having qualities of eloquence, ingenuity, or thievishness attributed to the god Mercury or to the influence of the planet Mercury

: characterized by rapid and unpredictable changeableness of mood <a mercurial temper>

: of, relating to, containing, or caused by mercury

— mer·cu·ri·al·ly \-ē-ə-lē\ adverb

— mer·cu·ri·al·ness noun

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Examples of MERCURIAL

Few moments in English history have been more hungry for the future, its mercurial possibilities and its hope of richness, than the spring of 1603. —Adam Nicolson, God's Secretaries, 2003
Though you could see all three places in one day, each of them makes you want to stay or to keep returning to watch the effects of the changing weather and the mercurial Sicilian light. —Francine Prose, Atlantic, December 2002
Some scientists suggest that because manic-depressive patients are ever riding the bio-chemical express between emotional extremes, their brains end up more complexly wired and remain more persistently plastic than do the brains of less mercurial sorts. —Natalie Angier, New York Times, 12 Oct. 1993
Still grinning, still miming, he samba-ed across the floor … and started in on the dishes with a vigor that would have prostrated his mercurial cousin. —T. Coraghessan Boyle, Harper's, October 1987
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Origin of MERCURIAL

(see mercury)

First Known Use: 14th century

Related to MERCURIAL

Synonyms: capricious, changeable, changeful, flickery, fluctuating, fluid, inconsistent, inconstant, fickle, mutable, skittish, temperamental, uncertain, unpredictable, unsettled, unstable, unsteady, variable, volatile

Antonyms: certain, changeless, constant, immutable, invariable, predictable, settled, stable, stationary, steady, unchangeable, unchanging, unvarying

Synonym Discussion of MERCURIAL

inconstant, fickle, capricious, mercurial, unstable mean lacking firmness or steadiness (as in purpose or devotion). inconstant implies an incapacity for steadiness and an inherent tendency to change <an inconstant friend>. fickle suggests unreliability because of perverse changeability and incapacity for steadfastness <performers discover how fickle fans can be>. capricious suggests motivation by sudden whim or fancy and stresses unpredictability <an utterly capricious critic>. mercurial implies a rapid changeability in mood <made anxious by her boss's mercurial temperament>. 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>.