The term 'on top' can be expressed in four different ways, each with five letters. The FIRST is 'UPON, ' which means to be placed or situated on something. The second is 'ALOFT, ' which means to be high up in the air. The third is 'AHEAD, ' which means to be in front of something. Finally, the fourth is 'FIRST, ' which means to be at the beginning or the top of something. All of these words express the idea of being on top or at the highest point.