grail [greyl]
noun

1.
( usually initial capital letter ) Also called Holy Grail. a cup or chalice that in medieval legend was associated with unusual powers, especially 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.