Definify.com
Webster 1913 Edition
Epact
E′pact
(ē′păkt)
, Noun.
[F.
épacte
, fr. Gr. ἐπακτόσ
brought on or in, added, fr. ἐπάγειν
to bring on or in; ἐπί
on, in + ἄγειν
to bring or lead. See Epi-
, and Act
.] (Chron.)
The moon’s age at the beginning of the calendar year, or the number of days by which the last new moon has preceded the beginning of the year.
Annual epact
, the excess of the solar year over the lunar year, – being eleven days.
– Menstrual epact
, or Monthly epact
the excess of a calendar month over a lunar.
Webster 1828 Edition
Epact
E'PACT
,Noun.
In chronology, the excess of the solar month above the lunar synodical month, and of the solar year above the lunar year of twelve synodical months. The epacts then are annual or menstrual. Suppose the new moon to be on the first of January; the month of January containing 31 days, and the lunar month only 29 days, 12h. 44'3', the difference, or 1 day, 11h. 15'57', is the menstrual epact. The annual epact is nearly eleven days; the solar year being 365 days, and the lunar year 354.
Definition 2024
epact
epact
English
Noun
epact (plural epacts)
- the time (number of days) by which a solar year exceeds twelve lunar months; it is used in the calculation of the date of Easter