Main entry: mercury, atomic number 80, quicksilver, Hg, hydrargyrum
Definition: a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures
Main entry: mercurial, erratic, fickle, quicksilver
Definition: liable to sudden unpredictable change
Usage: erratic behavior; fickle weather; mercurial twists of temperament; a quicksilver character, cool and willful at one moment, utterly fragile the next