The term 'diminish slowly' can be described by five different crossword solutions: TAPER (5 letters), WEAR (4 letters), FADE (4 letters), ERODE (5 letters), and WANE (4 letters). TAPER means to become gradually narrower towards one end, while WEAR means to diminish or impair through use or stress. FADE means to gradually grow faint or disappear, while ERODE means to gradually destroy or be worn away by natural forces. Lastly, WANE means to gradually decrease in size, strength, or intensity. All of these words describe the process of something diminishing slowly over time.