noun (n)

• a period of 10 years(noun.time)

  Synonym:
  decennary, decennium
  

  source: wordnet30
• the cardinal number that is the sum of nine and one; the base of the decimal system(noun.quantity)

  Synonym:
  10, ten, tenner, x
  

  source: wordnet30
• A group or division of ten; esp., a period of ten years; a decennium; as, a decade of years or days; a decade of soldiers; the second decade of Livy.(noun)

  source: webster1913