A chemical element, atomic number 7, atomic weight 14.007. It is a gas constituting about four-fifths of common air; chemically it is almost inert. It is not poisonous but is fatal if breathed alone because of oxygen deprivation. It is soluble in the blood and body fluids, and can cause serious symptoms when released as bubbles of gas by rapid decompression (see bends). Nitrogen occurs in proteins and amino acids and is thus present in all living cells.
Source: The Free Dictionary.