The term 'gradual' can be defined by the following crossword solutions: IMPERCEPTIBLE (13 letters), BEHIND (6 letters), GENTLE (6 letters), EASY (4 letters), MODERATE (8 letters), SLOW (4 letters), and stepwise (8 letters). Gradual is an adjective that describes a process or change that happens slowly over time, often in small increments. It is usually used to describe something that is not sudden or abrupt, but rather happens gradually and subtly. IMPERCEPTIBLE means so slight or gradual as to be almost unnoticeable, while BEHIND implies something that is lagging BEHIND or delayed. GENTLE and EASY both suggest something that is not too difficult or challenging, while MODERATE implies something that is of average difficulty. SLOW suggests something that is happening at a SLOW pace, and stepwise implies something that is happening in a series of steps or stages.