Dictionary entry

Metemptosis

Webster's Dictionary 1913

Met′emp‐to″sis (?), n.(Chron.) The suppression of a day in the calendar to prevent the date of the new moon being set a day too late, or the suppression of the bissextile day once in 134 years. The opposite to this is the proemptosis, or the addition of a day every 330 years, and another every 2,400 years.