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Mer·cu·ry

(mûrkyə-rē)

1. Roman Mythology A god that served as messenger to the other gods and was himself the god of commerce, travel, and thievery.

2. The smallest of the planets and the one nearest the sun, having a sidereal period of revolution about the sun of 87.97 days at a mean distance of 57.91 million kilometers (35.98 million miles) and a mean radius of approximately 2,440 kilometers (1,516 miles).

[Middle English Mercurie, from Old French, from Latin Mercurius.]

mer·cu·ry

(mûrkyə-rē)

1. Symbol HgA silvery-white poisonous metallic element, liquid at room temperature and used in thermometers, barometers, vapor lamps, and batteries and in the preparation of chemical pesticides. Atomic number 80; atomic weight 200.59; melting point -38.83°C; boiling point 356.62°C; specific gravity 13.546 (at 20°C); valence 1, 2.Also called quicksilver. See Periodic Table.

2. Temperature:The mercury had fallen rapidly by morning.

3. Any of several weedy plants of the genera Mercurialis and Acalypha.

[Middle Englishmercurie, fromMedieval Latinmercurius, fromLatinMercurius, Mercury.]

(click for a larger image)

Mercury

top: detail from a ceiling fresco by Giovanni Battista Tiepolo

bottom: false-color image of the planet Mercury

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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