The term 'POP UP AGAIN' can be summarized by two crossword solutions: 'RECUR' (5 letters) and 'REAPPEAR' (8 letters). Both words refer to the idea of something happening again, either after a period of time or in a repetitive manner. The term 'RECUR' is derived from the Latin word 'recurrere, ' which means 'to run back, ' while 'reappear' is derived from the Latin word 'reapparēre, ' which means 'to appear again.'