noun (n)

• a reference to yourself or myself etc.; `take care of number one' means to put your own interests first(noun.person)

  source: wordnet30
• the first or highest in an ordering or series(noun.linkdef)

  Synonym:
  first
  

  source: wordnet30
• the first element in a countable series(noun.quantity)

  Synonym:
  first, number 1
  

  source: wordnet30