Source : Webster's Revised Unabridged Dictionary (1913)

Peristalsis \Per`i*stal"sis\, n. [NL. See {Peristaltic}.]
   (Physiol.)
   Peristaltic contraction or action.

Source : WordNet®

peristalsis
     n : the process of wave-like muscle contractions of the
         alimentary tract that moves food along [syn: {vermiculation}]
         [ant: {anastalsis}]
     [also: {peristalses} (pl)]