[greyl] 
| 1. | (usually initial capital letter ) Also called Holy Grail. a cup or chalice that in medieval legend was associated with unusual powers, esp. the regeneration of life and, later, Christian purity, and was much sought after by medieval knights: identified with the cup used at the Last Supper and given to Joseph of Arimathea. |
| 2. | (sometimes initial capital letter) Informal. any greatly desired and sought-after objective; ultimate ideal or reward. |
| grail (grāl) n.
[Middle English greal, from Old French graal, from Medieval Latin gradālis, flat dish.] |
| Holy Grail n. See grail. |
A cup or bowl that was the subject of many legends in the Middle Ages. It was often said to have been used by Jesus at The Last Supper. The Grail was supposedly transported to Britain, where it became an object of quest for the knights of the Round Table.
Note: By extension, a “holy grail” is any esteemed object long sought for or attained only after great endeavor.