The term 'PRINCIPAL PRINCIPLE' is composed of two words: 'PRINCIPAL' and 'PRINCIPLE'. The word 'PRINCIPAL' is a noun meaning the head of a school or college, while the word 'PRINCIPLE' is a noun meaning a fundamental truth or law. The crossword solutions for this term are TAO (3 letters) and TENET (5 letters). TAO is a Chinese philosophical concept that emphasizes living in harmony with nature and the universe, while TENET is a Latin word meaning a belief or doctrine that is held to be true. Both words can be used to describe the concept of PRINCIPAL PRINCIPLE, which is the idea that a leader should act in accordance with fundamental truths and laws.