quicksilver (n.) Look up quicksilver at Dictionary.com
Old English cwicseolfor, literally "living silver," translating Latin argentum vivum (source also of Italian argento vivo), literally "living silver;" so called from its liquid mobility. See quick (adj.) + silver (n.). Similar formation in Dutch kwikzilver, Old High German quecsilbar, German quecksilber, French vif-argent, Italian argenta viva.