nitrogen

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A nonmetallic element that constitutes nearly four-fifths of the air by volume, occurring as a colorless, odorless, almost inert diatomic gas, N₂, in various minerals and in all proteins and used in a wide variety of important manufactures, including ammonia, nitric acid, TNT, and fertilizers. Atomic number 7; atomic weight 14.0067; melting point -209.86°C; boiling point -195.8°C; valence 3, 5. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, N; atomic weight, 14. An element existing in nature as a colorless, odorless, tasteless gas, reducible to a liquid under extreme pressure and cold. Its specific gravity is 9674. It is neither combustible nor a supporter of combustion, nor does it enter readily into combination with any other element. At a high temperature it unites directly with magnesium, silicon, chromium, and other metals. It forms about 77 per cent. of the weight of the atmosphere, and is a necessary constituent of all animal and vegetable tissues. In combination with hydrogen it forms the strong base ammonium, and with hydrogen and oxygen a series of acids of which nitric acid is commercially the most important. It may be most readily prepared from atmospheric air. There are five known compounds of nitrogen and oxygen—viz., nitrous oxid or nitrogen monoxid, N₂O; nitric oxid, N₂O₂; nitrogen trioxid, N₂O₃; nitrogen tetroxid, N₂O₄; nitrogen pentoxid, N₂O₅ Formerly called azote.
2. n. The boiling-point of liquid nitrogen under ordinary atmospheric pressure is -194.4° C. or -317.9° F. For the fixation of atmospheric nitrogen by growing plants, see nitragin.

Wiktionary

1. n. uncountable A chemical element (symbol N) with an atomic number of 7 and atomic weight of 14.0067.
2. n. uncountable Molecular nitrogen (N2), a colorless, odorless gas at room temperature.
3. n. countable A specific nitrogen within a chemical formula, or a specific isotope of nitrogen

GNU Webster's 1913

1. n. (Chem.) A colorless nonmetallic element of atomic number 7, tasteless and odorless, comprising four fifths of the atmosphere by volume in the form of molecular nitrogen (N2). It is chemically very inert in the free state, and as such is incapable of supporting life (hence the name azote still used by French chemists); but it forms many important compounds, such as ammonia, nitric acid, the cyanides, etc, and is a constituent of all organized living tissues, animal or vegetable. Symbol N. Atomic weight 14.007. It was formerly regarded as a permanent noncondensible gas, but was liquefied in 1877 by Cailletet of Paris, and Pictet of Geneva, and boils at -195.8 ° C at atmospheric pressure. Liquid nitrogen is used as a refrigerant to store delicate materials, such as bacteria, cells, and other biological materials.

WordNet 3.0

1. n. a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissues