The term 'be prostrate' can be broken down into three crossword solutions: PRONE (5 letters), LIE (3 letters), and LIETH (5 letters). PRONE means to be lying flat on one's stomach or face, while LIE means to be in a horizontal position on a surface. LIETH is an archaic form of the verb 'LIE, ' meaning to be in a reclining position. Together, these three words describe the act of being prostrate, which is to be lying flat on the ground in a humble or submissive manner.