The term 'First Principle' is often used to refer to the most basic or fundamental ELEMENT of something. The three crossword solutions for this term are 'RUDIMENT, ' 'ELEMENT, ' and 'SEED.' RUDIMENT is an 8-letter word meaning the basic elements or fundamentals of something, while ELEMENT is a 7-letter word referring to the essential parts of something. Lastly, SEED is a 4-letter word that can be used to describe the origin or starting point of something. All three words can be used to describe the concept of a First Principle, which is the most basic or fundamental ELEMENT of something.