Decline
Decay
noun, verbal noun
すいたい
悪化 （あっか） Deterioration, Getting Worse
劣化 （れっか） Deterioration, Degradation
衰退 （すいたい） Decline, Decay
He took his sweet すい time たい to Decline.
His sweet すい tie たい collection saw a Decline.
Sweet すい Thai たい food is in Decline.