Mer*cu"ri*al (?), a. [L.
mercurialis, fr. Mercurius Mercury: cf. F.
mercuriel.] 1. Having the qualities
fabled to belong to the god Mercury; swift; active; sprightly;
fickle; volatile; changeable; as, a mercurial youth; a
mercurial temperament.
A mercurial man
Who fluttered over all things like a fan.
Byron.
2. Having the form or image of Mercury; --
applied to ancient guideposts. [Obs.]
Chillingworth.
3. Of or pertaining to Mercury as the god of
trade; hence, money-making; crafty.
The mercurial wand of commerce.
J. Q. Adams.
4. Of or pertaining to, or containing,
mercury; as, mercurial preparations, barometer. See
Mercury, 2.
5. (Med.) Caused by the use of
mercury; as, mercurial sore mouth.
Mer*cu"ri*al, n. 1.
A person having mercurial qualities. Bacon.
2. (Med.) A preparation containing
mercury.