The term 'Complete Harmony' can be described as a state of perfect agreement and understanding between two or more people. The crossword solution for this term is 'UNISON', which means the simultaneous performance of a single action by multiple people. This term is often used in music, where it refers to the simultaneous performance of a single melody by multiple instruments or voices. It is also used in other contexts, such as politics, to describe a situation in which all parties involved are in agreement.