Quicksilver
WordNet
noun
(1) A heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures
WiktionaryText
Etymology
From from . Literally "living silver" from its ability to move. See in the sense of living.
Noun
- The metal mercury.
- An amalgam of mercury and tin applied to the backs of mirrors, quicksilvering.
Adjective
- Unpredictable, erratic or fickle; mercurial.