noun

1. Rom. Myth. the messenger of the gods, god of commerce, manual skill, eloquence, cleverness, travel, and thievery: identified with the Greek Hermes
2. the eighth largest planet in the solar system and the one nearest to the sun: diameter, c. 4,880 km (c. 3,030 mi); period of revolution, 87.97 earth days; period of rotation, 58.65 earth days; symbol, ☿

3. Etymology: ME < ML mercurius < L, Mercurius, Mercury: so named by the alchemists because of its fluidity: see quicksilver

   1. a heavy, silver-white metallic chemical element, liquid at ordinary temperatures, which sometimes occurs in a free state but usually in combination with sulfur; quicksilver: it is used in thermometers, air pumps, electrical products, etc. and in dentistry: symbol, Hg; at. no., 80
   2. the mercury column in a thermometer or barometer
4. pl. Mercuries -·riesNow Rare a messenger or guide
5. Bot.
   1. any of a genus (Mercurialis) of plants of the spurge family
   2. an edible European plant (Chenopodium bonus-henricus) of the goosefoot family

Etymology: L Mercurius, Mercury, of Etr orig.