What is the meaning of heaviness?

noun

• The property of being comparatively great in weight.
  • usage: "the heaviness of lead"
  • synonyms: weightiness
• Persisting sadness.
  • usage: "nothing lifted the heaviness of her heart after her loss"
• An oppressive quality that is laborious and solemn and lacks grace or fluency.
  • usage: "a book so serious that it sometimes subsided into ponderousness"; "his lectures tend to heaviness and repetition"
  • synonyms: ponderousness
• Used of a line or mark.
  • synonyms: thickness
• Unwelcome burdensome difficulty.
  • synonyms: burdensomeness, onerousness, oppressiveness