Merriam-Webster's Word of the Day for December 2, 2016 is:

wane \WAYN\ verb 1 : to decrease in size, extent, or degree 2 : to fall gradually from power, prosperity, or influence

Examples: "Last year, the station offered fans the chance to buy the CD online for the first time and also sold it in Target stores as usual. But unlike previous years, the limited-run compilation didn't sell out immediately, suggesting its popularity may be waning."