1. mercury, especially when in its liquid metallic form

1. moving or changing rapidly and unpredictably

Examples

• The old thermometer contained quicksilver that moved up and down with temperature changes.
• Quicksilver was once commonly used in barometers and other scientific instruments.
• Her quicksilver moods made it difficult to predict her reactions.
• The quicksilver movements of the dancer captivated the audience.
• His quicksilver wit allowed him to respond instantly to any question.
• The quicksilver nature of fashion trends makes it hard for retailers to keep up.