epact

American  

[ee-pakt] / ˈi pækt /

noun

1. the difference in days between a solar year and a lunar year.

2. the number of days since the new moon at the beginning of the calendar year, January 1.

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epact British  

/ ˈiːpækt /

noun

1. the difference in time, about 11 days, between the solar year and the lunar year

2. the number of days between the beginning of the calendar year and the new moon immediately preceding this

3. the difference in time between the calendar month and the synodic month

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Etymology

Origin of epact

1545–55; < Late Latin epacta < Greek epaktḗ, noun use of feminine of epaktós added, equivalent to ep- ep- + ag ( ein ) to lead + -tos verbid suffix

Example Sentences

See Examples For:

epact

Thus we have the epact, or age of the Calendar moon at the beginning of the year.

From A Budget of Paradoxes, Volume I by Smith, David Eugene

After which, from 1710 to 1900, a period of 190 years, according to Lilius’ own calculations, the epact is uniformly 11 days, coinciding exactly with the calculations made in this work.

From Our Calendar by Packer, George Nichols

This change takes place with epact 25 only, so that the computation of the lunar years may more closely respond to the solar year.

From The Divine Office by Quigley, Edward J.

It is, however, only used in those years in which the epact 19 concurs with the golden number 19.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" by Various

The value of L is always given by the formula for the dominical letter, and P and l are easily deduced from the epact, as will appear from the following considerations.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" by Various