metemptosis

from The Collaborative International Dictionary of English v.0.48

Metemptosis \Met`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.
   [1913 Webster]