pulsation

Short definition from Wiktionary

Noun

1. 1
   The regular throbbing of the heart, an artery etc. in a living body; the pulse.
2. 2
   Any rhythmic beating, throbbing etc.
3. 3
   The rhythmic increase and decrease of size in naked zoospores and plasmodia.
4. 4
   Physical striking; a blow.
5. 5
   A single beat, throb or vibration.