( also the Grail )
the plate or cup used by Jesus Christ at the Last Supper, in which some of his blood is said to have been collected after his death. There are many old stories about the Holy Grail. In the most famous of these King Arthur’s Knights of the Round Table go to search for it, and it is finally found by Sir Galahad , the only knight who is completely pure. When Galahad dies, his men see the Grail rise into Heaven. The expression Holy Grail is sometimes used to mean something very valuable which is very hard to find:
nuclear scientists seeking the holy grail of limitless energy.