noun
founder of a sect; originator; apostle
Primarily used for the founder of a religious sect or school of thought. Can also refer to the originator of a movement or invention, but less common than 創始者 or 創設者 in secular contexts.
彼はその新興宗教の開祖として知られている。
He is known as the founder of that new religious sect.
この哲学の開祖は古代ギリシャの思想家
The originator of this philosophy is an ancient Greek thinker.
Compound of 開 (kai, 'open, start') and 祖 (so, 'ancestor, founder'). The combination directly conveys the idea of a founding ancestor who opens a new tradition.