レーゾンデートル

noun

raison d'être; reason for being

A somewhat formal or philosophical term for the fundamental purpose or justification of someone's or something's existence. Often used in discussions of life purpose, art, or organizational mission.

from French

• 彼かれにとって音おん楽がくはレーゾンデートルだ。

  For him, music is his raison d'être.

• この会かい社しゃのレーゾンデートルは何なんですか？

  What is this company's reason for being?