"wane" in the noun sense
1. ebb, ebbing, wane
a gradual decline (in size or strength or power or number)
"wane" in the verb sense
1. decline, go down, wane
"Interest in the project waned"
"Interest in his novels waned"
decrease in phase
"the moon is waning"
Source: WordNet® (An amazing lexical database of English)
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