The term 'Ancient ONE' is often used to refer to a wise and powerful figure from the past. The crossword solution for this term is UNUM, which is a Latin word meaning 'ONE'. This term is often used to refer to a single entity that is greater than the sum of its parts, such as a deity or a powerful leader. It can also be used to describe something that has been around for a long time, such as an ancient civilization or a timeless tradition.