ˈēˌpakt, ˈeˌ- noun
( -s )
Etymology: Middle French epacte, from Late Latin epacta, from Greek epaktē, from feminine of epaktos, verbal of epagein to bring in, lead on, intercalate, teach by induction, from epi- + agein to lead, drive — more at agent
1.
a. : the number of days' difference between a lunar year and a solar year — called also annual epact
b. : the number of days' difference between a lunar month and a calendar month — called also menstrual epact
2. : the age in number of days of the moon at the beginning of the calendar year used in determining the date of Easter