The term 'decrease gradually' can be described by four different crossword solutions: TAPER (5 letters), LAG (3 letters), WANE (4 letters), and taperoff (8 letters). TAPER means to become gradually smaller or narrower in size, shape, or intensity. LAG means to fall behind in movement, progress, or development. WANE means to decrease gradually in size, strength, or intensity. Taperoff means to decrease gradually in size, strength, or intensity until it stops.