noun (n)

• (geology) the mechanical process of wearing or grinding something down (as by particles washing over it)(noun.process)

  Synonym:
  eating away, eroding, wearing, wearing away
  

  source: wordnet30
• condition in which the earth's surface is worn away by the action of water and wind(noun.state)

  source: wordnet30
• a gradual decline of something(noun.process)

  Example:
  After the accounting scandal there was an erosion of confidence in the auditors.
  

  source: wordnet30
• erosion by chemical action(noun.process)

  Synonym:
  corroding, corrosion
  

  source: wordnet30
• The act or operation of eroding or eating away.(noun)

  source: webster1913
• The wearing away of the earth's surface by any natural process. The chief agent of erosion is running water; minor agents are glaciers, the wind, and waves breaking against the coast.(noun)

  source: webster1913