epact definition by Webster's New World
- the period of about eleven days by which the solar year exceeds the lunar year of twelve months
- the age, in days, of the calendar moon on the first of the year
Origin: French épacte ; from Late Latin epactae ; from Classical Greek epaktai (hemerai), intercalary (days) ; from epagein, to bring in, intercalate ; from epi-, on, in plush agein, to bring, lead: see act
epact definition by American Heritage Dictionary
Origin: 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.