mercury

n. 1 silvery heavy liquid metallic element used in barometers, thermometers, etc. 2 (mercury) planet nearest to the sun.  mercuric adj. Mercurous adj. [latin mercurius, roman messenger-god]

n. A Latin god of commerce and gain; -- treated by the poets as identical with the Greek Hermes, messenger of the gods, conductor of souls to the lower world, and god of eloquence.