(1):

(a.) Having the form or image of Mercury; - applied to ancient guideposts.

(2):

(a.) Having the qualities fabled to belong to the god Mercury; swift; active; sprightly; fickle; volatile; changeable; as, a mercurial youth; a mercurial temperament.

(3):

(n.) A person having mercurial qualities.

(4):

(a.) Of or pertaining to Mercury as the god of trade; hence, money-making; crafty.

(5):

(a.) Of or pertaining to, or containing, mercury; as, mercurial preparations, barometer. See Mercury, 2.

(6):

(a.) Caused by the use of mercury; as, mercurial sore mouth.

(7):

(n.) A preparation containing mercury.