The term "waning" in moon phases means that the illuminated portion of the Moon visible from Earth is getting smaller each night. This occurs after the full moon phase as the Moon moves toward the new moon phase

. During the waning phases, the bright part of the Moon gradually decreases, while the shadowed part increases. The waning period includes three specific phases:

• Waning Gibbous: More than half of the Moon is illuminated, but the lighted area is shrinking, typically on the left side as seen from the Northern Hemisphere.
• Third (or Last) Quarter: Half of the Moon is illuminated on the left side, and half is in shadow.
• Waning Crescent: A thin crescent of light remains on the left side, shrinking until the new moon

In summary, a waning moon is any phase between the full moon and new moon when the visible illuminated surface is decreasing in size