#1 Mercurial s. [erratic, fickle, mercurial, quicksilver] liable to sudden unpredictable change; "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next". wn
#2 Mercurial a. relating to or under the (astrological) influence of the planet Mercury; "the Mercurial canals". wn
#3 Mercurial a. relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury; "more than Mercurial thievishness". wn
#4 Mercurial a. [mercurial] relating to or containing or caused by mercury; "mercurial preparations"; "mercurial sore mouth". wn
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