noun
- The number of days by which the solar year exceeds the lunar year, used in calculating the date of Easter.
Usage: technical; ecclesiastical
Examples
- The epact is essential for determining when Easter falls each year.
- Astronomers use the epact to reconcile the lunar and solar calendars.
- The epact value changes annually and is used in the Computus calculation.
- Medieval monks carefully tracked the epact to maintain accurate liturgical calendars.