üleliigpäevad

üleliigpäevad refers to leap days in Estonian. A leap day is an extra day added to the calendar to keep it synchronized with the astronomical year. In the Gregorian calendar, which is widely used, this extra day is added every four years, specifically on February 29th. This system is designed to account for the fact that the Earth's orbit around the sun takes approximately 365.2422 days, rather than a precise 365 days. Without the addition of leap days, the calendar would gradually drift out of sync with the seasons.

The rule for determining leap years is that a year is a leap year if it is divisible by four, except for end-of-century years, which must be divisible by 400. For example, the year 2000 was a leap year because it is divisible by 400, but the year 1900 was not a leap year because it is divisible by 100 but not by 400. The concept of a leap day has been implemented in various calendar systems throughout history, with different methods for synchronization. The term "üleliigpäevad" directly translates to "superfluous days" or "extra days," highlighting their additive nature to the standard calendar.