gradual
/ˈgrædʒuəl; `ɡrædʒʊəl/ adj
(a) taking place by a series of small changes over a long period; not sudden 逐渐的; 渐变的
gradual decline, progress, etc 逐渐的衰落、 进步等
a gradual increase, decrease, recovery 逐渐的增加、 减少、 恢复.
(b) (of a slope) not steep （指斜坡）不陡峭的, 和缓的
a gradual rise, fall, incline, etc 渐起、 渐落、 渐降.