noun
emperor's gift cup
A cup bestowed by the emperor, typically as an honor or prize. This is a historical or ceremonial term; not used in everyday conversation.
彼は競技会で優勝し、天皇から天杯を授与された。
He won the competition and was presented with an emperor's gift cup by the Emperor.
Compound of 天 (ten, 'emperor' or 'heavenly') and 杯/盃 (hai, 'cup' or 'sake cup'). The exact historical origin is uncertain, but it refers to a cup given by the emperor.