waning

To progressively lose its splendor, value, ardor, power, intensity etc.; to decline.

Said of light that dims or diminishes in strength.

Said of the Moon as it passes through the phases of its monthly cycle where its surface is less and less visible.

Said of a time period that comes to an end.

To decrease physically in size, amount, numbers or surface.

To cause to decrease.

Becoming weaker or smaller.

“his waning strength”

Of the lunar phase: as it shrinks when viewed from the Earth.

“the waning moon”

The fact or act of becoming less or less intense.

“the waning of her energy”

The fact or act of becoming smaller.