mercurial

[mer-kyoor-ee-uhl]

adjective

1. changeable; volatile; fickle; flighty; erratic.

   a mercurial nature.

   Synonyms: indecisive, inconstant
   Antonyms: steady, constant

2. animated; lively; sprightly; quick-witted.

   Synonyms: spirited
   Antonyms: phlegmatic

3. pertaining to, containing, or caused by the metal mercury.

4. (initial capital letter),  of or relating to the god Mercury.

5. (initial capital letter),  of or relating to the planet Mercury.

noun

1. Pharmacology.,  a preparation of mercury used as a drug.

mercurial

/ mɜːˈkjʊərɪəl /

adjective

1. of, like, containing, or relating to mercury

2. volatile; lively

   a mercurial temperament

3. (sometimes capital) of, like, or relating to the god or the planet Mercury

noun

1. med any salt of mercury for use as a medicine

Other Word Forms

• mercurially adverb
• mercurialness noun
• mercuriality noun
• unmercurial adjective
• unmercurially adverb
• unmercurialness noun

Word History and Origins

Origin of mercurial¹

First recorded in 1350–1400; Middle English, from Latin mercuriālis “of or pertaining to the god or planet Mercury”; mercury, -al ¹

Word History and Origins

Origin of mercurial¹

C14: from Latin mercuriālis

Example Sentences

Many people who knew her described her as unstable and mercurial.

From Los Angeles Times

The mercurial Spaniard had become the first European to win the Masters in 1980, adding to his 1979 Open triumph, but was at loggerheads with the tour over appearance fees.

From BBC

But after an encouraging week against the last-place Colorado Rockies, the Dodgers’ mercurial offense once again went missing.

From Los Angeles Times

It is the story of Mary Roy, her formidable, mercurial mother: feminist icon, educator, crusader, eccentric, bully, inspiration.

From BBC

As Timothy, an old acting school buddy of the Clooney-esque Kelly, Crudup brings a mercurial intensity to a pivotal early scene that begins with warmth and ends in rage.

From Los Angeles Times

Related Words

• changeable 
• effervescent 
• erratic 
• impulsive 
• resilient 
• unpredictable 
• volatile