What is the meaning of waning?

noun

• A gradual decrease in magnitude or extent.
  • usage: "the waning of his enthusiasm was obvious"; "the waxing and waning of the moon"

verb

• Grow smaller.
  • usage: "Interest in the project waned"
  • synonyms: decline, go down, wane
• Become smaller.
  • usage: "Interest in his novels waned"
  • synonyms: wane
• Decrease in phase.
  • usage: "the moon is waning"
  • synonyms: wane

adjective

• Of the Moon. ( pertaining to the period during which the visible surface of the moon decreases)
  • usage: "after full moon comes the waning moon"