Definitions
1.adjectiveHaving an intercalary day, particularly the quadrennial leap day of the Julian and Gregorian calendars traditionally placed as a "second sixth" day before March 1st.
2.nounA year in the Julian or Gregorian calendars with an intercalary day added to February, used to adjust for the extra hours of the solar year; a 366-day year.
3.noun(inexact) Any other year featuring intercalation, such as a year in a lunisolar calendar with 13 months instead of 12, used to maintain its alignment with the seasons of the solar year.