Earth & SkyGreek → English
Epact
/ˈiːpækt/noun
The age of the moon on the first of January, used to calculate the date of Easter.
The Greek roots
ἐπί
epí
upon, in addition
ἄγειν
ágein
to lead, bring
Literally: “days brought in”
The story of the word
The full Greek phrase was ἐπακταὶ ἡμέραι, brought-in days: the extra days you add to twelve lunar months to catch up with the sun. Church computists reduced it to a single number, the moon's age at the start of the year, from which the whole Easter table can be worked out. The usual gap is eleven days, so the epact climbs by eleven each year and drops by thirty whenever a full lunar month has piled up.
- How it travelled
- Ancient Greek → Late Latin → French → English
- First recorded
- 16th century
Same family
synagoguepedagoguedemagoguestrategy
In a sentence
Every medieval calendar page carries a golden number and an epact in the margin.
He could still work out the epact by hand, which nobody had asked him to do.