What is the meaning of intensity?

noun

• The amount of energy transmitted (as by acoustic or electromagnetic radiation. )
  • usage: "he adjusted the intensity of the sound"; "they measured the station's signal strength"
  • synonyms: strength, intensity level
• High level or degree; the property of being intense.
  • synonyms: intensiveness
• The magnitude of sound (usually in a specified direction. )
  • usage: "the kids played their music at full volume"
  • synonyms: volume, loudness
• Chromatic purity: freedom from dilution with white and hence vivid in hue.
  • synonyms: saturation, chroma, vividness