The term 'Period of Decline' can be described by the crossword solutions TWILIGHT (8 letters), SUNSET (6 letters), EBB (3 letters), DOTAGE (6 letters), SLUMP (5 letters), Ebbtide (7 letters), and Lowtide (7 letters). TWILIGHT is a time of day when the sun is setting, and SUNSET is the end of the day when the sun disappears below the horizon. EBB is a gradual decrease in something, such as a tide or a river's flow. DOTAGE is a state of mental or physical decline due to old age. SLUMP is a period of economic decline, and Ebbtide and Lowtide are both terms used to describe the lowest point of a tide. Together, these words all describe a period of decline, whether it be physical, mental, economic, or environmental.