noun (n)

• an undulating curve(noun.shape)

  Synonym:
  wave
  

  source: wordnet30
• wavelike motion; a gentle rising and falling in the manner of waves(noun.event)

  source: wordnet30
• (physics) a movement up and down or back and forth(noun.event)

  source: wordnet30
• The act of undulating; a waving motion or vibration; as, the undulations of a fluid, of water, or of air; the undulations of sound.(noun)

  source: webster1913