Other forms: grails
A grail is some valuable thing you search for or pursue. A golfer's holy grail might be a hole in one.
While the object of any serious pursuit is commonly described as a "holy grail," many who use the term might not know its origin. The original Holy Grail is a valuable chalice, cup, or plate — often made of gold — that's sought in medieval and Arthurian legends. The influence of Christianity makes the grail "holy," originally because it was said to have been used at the Last Supper. Grail has a Medieval Latin root, gradalis, "flat dish."