The term THREE IN ONE can be summarized in two different ways. The first is TRIUNE, which is a six-letter word meaning 'three in one'. This term is often used to refer to the Christian concept of the Trinity, which is the belief that God is three persons in one being. The second is TRIUNITY, which is an eight-letter word meaning 'the state of being three in one'. This term is often used to refer to the unity of the three persons of the Trinity.