The Decreasing in Size of the Visible Moon

This page is the CodyCross answer for the clue below from Futuristic City , Group 999, Puzzle 2 (Suspended Animation).

Question is: The Decreasing in Size of the Visible Moon

and the answer is: WANING

Word Meaning:

WANING — present participle and gerund of wane

Definitions from Wiktionary.