epact
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e·pact
(ē′păkt′)n.
The period of time necessary to bring the solar calendar into harmony with the lunar calendar.
[French épacte, from Late Latin epacta, from Greek epaktē (hēmera), intercalary (day), feminine of epaktos, brought in, inserted, from epagein, to bring in, introduce : ep-, epi-, epi- + agein, to lead; see ag- in Indo-European roots.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
epact
(ˈiːpækt)n
1. (Astronomy) the difference in time, about 11 days, between the solar year and the lunar year
2. (Astronomy) the number of days between the beginning of the calendar year and the new moon immediately preceding this
3. (Horology) the difference in time between the calendar month and the synodic month
[C16: via Late Latin from Greek epaktē, from epagein to bring in, intercalate, from agein to lead]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
e•pact
(ˈi pækt)n.
the difference in days between a solar year and a lunar year: a period of time added to a calendar to harmonize the two.
[1545–55; < Middle French epacte < Late Latin epactae < LGK epaktaí(hēmérai) intercalated (days), pl. of epaktós <epágein to bring in, intercalate]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.