Mercurial 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. [1913 Webster]

A mercurial man Who fluttered over all things like a fan. --Byron. [1913 Webster]

2. Having the form or image of Mercury; -- applied to ancient guideposts. [Obs.] --Chillingworth. [1913 Webster]

3. Of or pertaining to Mercury as the god of trade; hence, money-making; crafty. [1913 Webster]

The mercurial wand of commerce. --J. Q. Adams. [1913 Webster]

4. Of or pertaining to, or containing, mercury; as, mercurial preparations, barometer. See {Mercury}, 2. [1913 Webster]

5. (Med.) Caused by the use of mercury; as, mercurial sore mouth. [1913 Webster]

The Collaborative International Dictionary of English. 2000.