|the oxygen-carrying pigment of red blood cells that gives them their red color and serves to convey oxygen to the tissues: occurs in reduced form|
|the most important of the male sex hormones, both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty|
|a. a colourless odourless relatively unreactive gaseous element that forms 78 per cent (by volume) of the air, occurs in many compounds, and is an essential constituent of proteins and nucleic acids: used in the manufacture of ammonia and other chemicals and as a refrigerant. Symbol: N; atomic no: 7; atomic wt: 14.00674; valency: 3 or 5; density: 1/2506 kg/m³; melting pt: --210.00°C; boiling pt: --195.8°C|
|b. (as modifier): nitrogen cycle|
nitrogen ni·tro·gen (nī'trə-jən)
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. Atomic number 7; atomic weight 14.0067; melting point -210.00°C; boiling point -195.8°C; valence 3, 5.
|nitrogen (nī'trə-jən) Pronunciation Key
A nonmetallic element that makes up about 78 percent of the atmosphere by volume, occurring as a colorless, odorless gas. It is a component of all proteins, making it essential for life, and it is also found in various minerals. Nitrogen is used to make 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 Periodic Table. See Note at oxygen.