The Collaborative International Dictionary of English v.0.48:

Nitrogen \Ni`tro*gen\ (n[imac]"tr[-o]*j[e^]n), n. [L. nitrum
   natron + -gen: cf. F. nitrog[`e]ne. See Niter.] (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 [deg] C at atmospheric pressure. Liquid
   nitrogen is used as a refrigerant to store delicate
   materials, such as bacteria, cells, and other biological
   materials.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

nitrogen
    n 1: 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 [syn: nitrogen, N, atomic number 7]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "nitrogen":
   acetylene, ammonia, argon, asphyxiating gas, butane,
   carbon dioxide, carbon monoxide, castor-bean meal, chlorine,
   coal gas, commercial fertilizer, compost, dressing, dung,
   enrichener, ethane, ether, ethylene, fertilizer, fluorine,
   formaldehyde, guano, helium, hydrogen, illuminating gas, krypton,
   lewisite, manure, marsh gas, methane, muck, mustard gas,
   natural gas, neon, night soil, nitrate, organic fertilizer, oxygen,
   ozone, phosphate, poison gas, propane, radon, sewer gas,
   superphosphate, xenon



The Elements (07Nov00):

nitrogen
Symbol: N
Atomic number: 7
Atomic weight: 14.0067
Colourless, gaseous element which belongs to group 15 of the periodic
table. Constitutes ~78% of the atmosphere and is an essential part of
the
ecosystem. Nitrogen for industrial purposes is acquired by the
fractional
distillation of liquid air. Chemically inactive, reactive generally only
at high temperatures or in electrical discharges. It was discovered in
1772 by D. Rutherford.