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).