NA - Definition

WordNet Dictionary

	Definition:	[n] a silvery soft waxy metallic element of the alkali metal group; occurs abundantly in natural compounds (especially in salt water); burns with a yellow flame and reacts violently in water; occurs in sea water and in the mineral halite (rock salt)

	Websites:

	Synonyms:	atomic number 11, sodium

	See Also:	brine, halite, metal, metallic element, rock salt, saltwater, seawater

Webster's 1913 Dictionary

	Definition:	\Na\ (n[aum]), a. & adv. No, not. See {No}. [Obs.] --Chaucer.

Computing Dictionary

	Definition:	The country code for Namibia.

Biology Dictionary

	Definition:	Sodium is a soft, silvery, highly reactive alkali metal which has an atomic number of 11 and an atomic weight of 22.990. It is most commonly found in the form of salt, sodium chloride (NaCl). It was first identified as an element by the English scientist Sir Humphrey Davy in 1807. Sodium chloride is a critical nutrient in humans (it plays an important role in nerve function), but too much of it can cause health problems such as aggravating high blood pressure. Pure metallic sodium is a fire hazard, and it can explode if it comes into contact with water. Other commonly used sodium compounds include soda ash (sodium carbonate, Na₂CO₃), baking soda (sodium bicarbonate, NaHCO₃) and caustic soda (sodium hydroxide, NaOH).