grail
n. countable C2 Proficiency US //ˈɡɹeɪɫ// UK //ɡɹˈeɪl// grail
n. something that you want very much but is extremely difficult to find or achieve.
n. the object of a prolonged or difficult quest; a goal that is highly sought after but elusive. When capitalised, it refers to the cup used by Jesus at the Last Supper in medieval legend.
Finding a cure for the common cold is the medical grail.
For many vintage car collectors, finding an original 1960s model in perfect condition is the ultimate grail.
Physicists have long pursued a unified theory of everything, viewing it as the holy grail of modern science that would reconcile gravity with quantum mechanics.
Usage
Often used in the idiomatic phrase 'the holy grail' to describe a supreme goal.