the world > the universe > planet > primary planet > moon > phase > pass through phase [verb (intransitive)] > wane (3)
Of the moon: To undergo the periodical decrease in the extent of its visible illuminated portion, characteristic of the second half of the lunation.
intransitive. To decrease, to grow less (literal and figurative); esp. (of the moon) to wane.
Of material things: To be used up or worn away; to lose substance or volume by gradual loss or wear or decay. †Of the moon: To wane (obsolete).