epact means 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. Lexicurio rates it Sui generis — a strength score of 93 out of 100.
Why “epact” is a great word
EPACT — [Noun] The number of days by which the solar year exceeds twelve lunar months, used to reconcile lunar and solar calendars in the computation of Easter. From French épacte, from Latin epactae, from Ancient Greek ἐπακταί (epaktaí, "intercalary days"), feminine plural of ἐπακτός (epaktós, "brought in or added"), from ep- ("on, upon") + ag(ein) ("to lead, bring"). First attested in English 1545–55. Unlike "intercalation" (which names the general act of inserting a corrective day or month) or the "golden number" (which marks a year's place in a 19-year lunar cycle), the epact is the precise, numerical discrepancy itself—the spare days left over. It is the ghostly remainder in a celestial long-division problem, the silent eleven-day drift of the moon from the sun each year, and the arithmetical secret scratched in the margins of old almanacs—a mathematical sigh against the imperfect marriage of heaven and our reckoning of time.
noun
- 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