MetemptosisMet`emp*to"sis\, n. [NL., from Gr. ? beyond, after + ? a falling upon, fr. ? to fall in or upon; ? in + ? to fall.] (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.