The crossword solution for the term P, TO PLATO is RHO, which is a three-letter word. RHO is the 17th letter of the Greek alphabet and is often used in mathematics and science. It is also used to represent the density of a fluid or gas. In philosophy, Plato was an ancient Greek philosopher who is considered one of the most influential thinkers in Western philosophy. He is known for his dialogues and theories on justice, beauty, and the forms of knowledge.