The term 'KNIGHTS' Quest' is often used to refer to the search for the Holy GRAIL, a legendary object associated with Christianity. The crossword solution for this term is 'GRAIL', which is a five-letter word. The GRAIL is believed to have been the cup used by Jesus at the Last Supper and is said to have miraculous powers. It has been the subject of many stories and quests throughout history, most famously in the Arthurian legend.