The term 'cease activity' can be summarized by two crossword solutions: REST (4 letters) and STAGNATE (8 letters). REST is defined as a state of inactivity or repose, while STAGNATE is defined as to become inactive or dull. Both terms refer to the cessation of activity, either voluntarily or involuntarily. REST implies a conscious decision to stop activity, while STAGNATE implies that activity has stopped due to a lack of progress or development. In either case, the result is a lack of movement or progress.