changeable; volatile; fickle; flighty; erratic: a mercurial nature.
animated; lively; sprightly; quick-witted.
pertaining to, containing, or caused by the metal mercury.
(initial capital letter) of or relating to the god Mercury.
(initial capital letter) of or relating to the planet Mercury.


Pharmacology. a preparation of mercury used as a drug.

Origin of mercurial

1350–1400; Middle English < Latin mercuriālis of, pertaining to the god or planet Mercury. See mercury, -al1
Related formsmer·cu·ri·al·ly, adverbmer·cu·ri·al·ness, mer·cu·ri·al·i·ty, nounun·mer·cur·i·al, adjectiveun·mer·cur·i·al·ly, adverbun·mer·cur·i·al·ness, noun

Synonyms for mercurial

Antonyms for mercurial Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for mercurial

Contemporary Examples of mercurial

Historical Examples of mercurial

  • Of a fiery, mercurial disposition, his temper flew in a moment.

    War from the Inside

    Frederick L. (Frederick Lyman) Hitchcock

  • He is of that deep, mercurial disposition that attracts women.

  • The champagne was bubbling trickily in the veins of the mercurial statesmen.

  • Vidi, measures approximately, but not with the permanence of the mercurial.

    The Sailor's Word-Book

    William Henry Smyth

  • He took iodide of potassium for a time after his mercurial course.

    The Electric Bath

    George M. Schweig

British Dictionary definitions for mercurial



of, like, containing, or relating to mercury
volatile; livelya mercurial temperament
(sometimes capital) of, like, or relating to the god or the planet Mercury


med any salt of mercury for use as a medicine
Derived Formsmercurially, adverbmercurialness or mercuriality, noun

Word Origin for mercurial

C14: from Latin mercuriālis
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for mercurial

late 14c., "pertaining to the planet Mercury" (see Mercury). Meaning "sprightly, volatile, quick" (1590s) is from supposed qualities of those born under the planet Mercury (they also are the qualities of the god Mercury), probably also partly by association with the qualities of quicksilver. A variant in this sense was mercurious (1590s). Related: Mercurially; mercuriality.

Online Etymology Dictionary, © 2010 Douglas Harper

mercurial in Medicine




Containing or caused by the action of the element mercury.


A pharmacological or chemical preparation containing mercury.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.