The term 'APPROACHED RAPIDLY' can be broken down into four crossword solutions: SPED (4 letters), RANTO (5 letters), RANUPTO (7 letters), and BOREDOWNON (10 letters). SPED is an acronym for 'SPEED', which means to move quickly. RANTO is a combination of the words 'RAN' and 'ONTO', which implies that something was running towards something else. RANUPTO is a combination of the words 'RAN' and 'up to', which suggests that something was running towards a certain point. Finally, BOREDOWNON is a combination of the words 'BORE' and 'down on', which implies that something was moving quickly and forcefully towards a certain point. All of these words together suggest that something was approaching rapidly.