The term 'DROPS BELOW THE HORIZON' can be broken down into two crossword solutions: SETS (4 letters) and SINKS (5 letters). The term 'sets' refers to the sun or moon setting below the horizon, which is when it appears to disappear from view. This occurs when the sun or moon moves below the observer's line of sight. The term 'sinks' refers to the sun or moon sinking below the horizon, which is when it appears to move further away from the observer. Both terms refer to the same phenomenon, but from different perspectives.