mercury

noun

1. 1

   the smallest planet and the nearest to the sun

   the mercury was falling rapidly

2. 2

   temperature measured by a mercury thermometer

   the mercury was falling rapidly

3. 3

   (Roman mythology) messenger of Jupiter and god of commerce; counterpart of Greek Hermes

4. 4

   a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures