- of, like, containing, or relating to mercury
- volatile; lively: a mercurial temperament
- (sometimes capital) of, like, or relating to the god or the planet Mercury
- any salt of mercury for use as a medicine
WordReference Random House Learner's Dictionary of American English © 2026
mer•cu•ri•al /mərˈkyʊriəl/USA pronunciation adj.
WordReference Random House Unabridged Dictionary of American English © 2026- changeable;
varying;
erratic:a mercurial nature; a mercurial mood.
mer•cu•ri•al
(mər kyŏŏr′ē əl),USA pronunciation adj.
n.
mer•cu ′ri•al•ly, adv.
mer•cu ′ri•al•ness, mer•cu′ri•al′i•ty, n.
- changeable;
volatile;
fickle;
flighty;
erratic:a mercurial nature. - animated;
lively;
sprightly;
quick-witted. - Chemistrypertaining to, containing, or caused by the metal mercury.
- Mythology(cap.) of or pertaining to the god Mercury.
- Astronomy(cap.) of or pertaining to the planet Mercury.
n.
- Drugs[Pharm.]a preparation of mercury used as a drug.
- Latin mercuriālis of, pertaining to the god or planet Mercury. See mercury, -al1
- Middle English 1350–1400
mer•cu ′ri•al•ness, mer•cu′ri•al′i•ty, n.
- 1. . inconstant, indecisive. 2. . spirited.
- 1. . constant, steady. 2. . phlegmatic.
Collins Concise English Dictionary © HarperCollins Publishers::
mercurial /mɜːˈkjʊərɪəl/ adj