"Interest in the project waned"
"Interest in his novels waned"
"the moon is waning"
She, like a moon in wane, Faded before him.
That which grows is said to wax, and that which decays to wane.
牛津高階第八版
美國韋氏詞典
Dictionary.com
Free Dictionary
維基百科 (自由的百科全書)