noun (n)

• one of the twelve divisions of the calendar year(noun.time)

  Example:
  He paid the bill last month.
  

  Synonym:
  calendar month
  

  source: wordnet30
• a time unit of approximately 30 days(noun.time)

  Example:
  He was given a month to pay the bill.
  

  source: wordnet30
• One of the twelve portions into which the year is divided; the twelfth part of a year, corresponding nearly to the length of a synodic revolution of the moon, -- whence the name. In popular use, a period of four weeks is often called a month.(noun)

  source: webster1913