waning

The act or process of waning, or decreasing.

Becoming weaker or smaller.

Especially of the lunar phase as it shrinks when viewed from the Earth.

The fact or act of becoming less or less intense.

The fact or act of becoming smaller.

Present participle of wane.

(of the Moon) pertaining to the period during which the visible surface of the moon decreases

a gradual decrease in magnitude or extent