noun (n)

• a period of time containing 365 (or 366) days(noun.time)

  Example:
  She is 4 years old.
  In the year 1920.
  

  Synonym:
  twelvemonth, yr
  

  source: wordnet30
• a period of time occupying a regular part of a calendar year that is used for some particular activity(noun.time)

  Example:
  A school year.
  

  source: wordnet30
• the period of time that it takes for a planet (as, e.g., Earth or Mars) to make a complete revolution around the sun(noun.time)

  Example:
  A Martian year takes 687 of our days.
  

  source: wordnet30
• a body of students who graduate together(noun.group)

  Example:
  She was in my year at Hoehandle High.
  

  Synonym:
  class
  

  source: wordnet30
• The time of the apparent revolution of the sun trough the ecliptic; the period occupied by the earth in making its revolution around the sun, called the astronomical year; also, a period more or less nearly agreeing with this, adopted by various nations as a measure of time, and called the civil year; as, the common lunar year of 354 days, still in use among the Mohammedans; the year of 360 days, etc. In common usage, the year consists of 365 days, and every fourth year (called bissextile, or leap year) of 366 days, a day being added to February on that year, on account of the excess above 365 days (see Bissextile).(noun)

  source: webster1913