(uranography) Winter Triangle - a bright asterism of the northern winter sky. Its corners are the stars Betelgeuse, Procyon, and Sirius.

(uranography) Summer Triangle - a bright asterism of the northern summer sky. Its corners are the stars Altair, Deneb, and Vega.

Kyūjitai form of 三位一体 (“Trinity”)

three-legged race / (idiomatic) cooperating and working together to accomplish a task

dirt cheap

(religion, Buddhism) Trailokyavijaya, the Wisdom King of the east, primarily revered in Vajrayana Buddhism

(Christianity) the Trinity

the Three Sovereigns and Five Emperors

the Thirty-Six Stratagems

(historical) Chinese equivalent of 准大臣 (Jun-daijin): title of an honorary grand minister equal to a vice-daijin; in the same honors between the 内大臣 (naidaijin, “minister of the center”) and the 大納言 (dainagon, “upper counselor”)