366 days 366 days /θri ˈsɪkstiˈsɪks deɪz/

noun

1. In the Gregorian calendar, a year with 366 days including 29th February; usually any year divisible by 4 is a leap year, with the exception that centenary years are not leap years unless divisible by 400  ( 366 days , bissextile year , intercalary year , leap year )
   In the Gregorian calendar, a year with 366 days including 29th February; usually any year divisible by 4 is a leap year, with the exception that centenary years are not leap years unless divisible by 400