#undulation__wave  (physics) a progressive disturbance propagated without displacement of the medium itself
  supertype:  #periodic_event__recurrent_event__recurrentevent  an event that recurs at intervals
  subtype:  #gravity_wave  #sine_wave  #vibration  #fluctuation  #seiche  #standing_wave  #sound_wave  #waveform  #pulsing  #flapping
  part:  #wave_front  all the points just reached by a wave as it propagates

No statement uses or specializes #undulation; click here to add one.