quicksilver Meaning, Definition & Usage

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

WordNet

Quick"sil`ver noun
Etymology
Quick living + silver; -- so called from its fluidity; cf. G. quecksilber, L. argentum vivum. See Quick, a.
Definitions
  1. (Chem.) The metal mercury; -- so called from its resemblance to liquid silver.

Webster 1913