grail

A grail is a type of cup, chalice, goblet, or vessel. But the word is almost always used to mean the Holy Grail or a holy grail.

When capitalized, Holy Grail (or just Grail) refers to the cup that according to medieval legend was used by Jesus at the Last Supper. Due to legends about the cup’s supposed powers, it became the subject of quests by knights who hoped to locate it, including the legendary King Arthur and his Knights of the Round Table. (A somewhat similar legend is that of El Dorado, the legendary city of gold and treasure sought by Spanish colonizers.)

This sense of Holy Grail and Grail eventually came to be used (often in lowercase) in a metaphorical way to refer to any greatly desired and sought-after objective, reward, item, or ultimate ideal. For example, a particularly rare book may be called the holy grail of rare book collecting, or winning the World Cup may be called the holy grail of soccer (football). Such things are often described as highly sought-after.

A person’s ultimate desire may be called their grail. A similar term is heart’s desire. Similar but less idiomatic terms are ultimate prize and ultimate goal.