Trinity, The. A predominantly Christian understanding of the inner nature of the Godhead. Trinitarian understandings of God may arise primarily from revelation, as Christians affirm, but they are more widely embedded in a belief that there is an analogical relationship between God and the created or manifest world (see ANALOGY): since in this world it is only possible to be a self in a field of selves, the inference is drawn that the interior nature of God must be relational, and not monistically abstract. Among Hindus, the relational character of God may be dipolar, with opposites united in a single character and action, but equally, as in the Trimūrti emphasis, it may be of far greater complexity. None of this contradicts the insistence in Islam (though many Muslims suppose that it does) on tawḥīd, the absolute unity of God, since whatever God may turn out to be, it can only be God that God turns out to be—though it so happens that that nature is relational: see also SAN-I in Taoism; TRIKĀYA in Buddhism.

It is, however, in Christianity that the Trinitarian nature of God has been most complexly explored, affirming that there is the one God, who exists in three persons: Father, Son, and Holy Spirit. The basis for this doctrine in the Bible consists of threefold formulae like Matthew 28. 19; 1 Peter 1. 2, and Isaiah 6. 3. These passages in no way predicate a God who is eternally three in one, but they set the terms for later thinking toward that end. In the 3rd and early 4th cents., against Sabellianism and Arianism, the Son and Father were defined as distinct yet coequal and coeternal. In the late 4th cent. the Cappadocian Fathers took the final step by understanding the Holy Spirit as of the same status. God was then to be spoken of as one ousia (being) in three hypostases (persons), and this has remained the orthodox formulation.

Many modern scholars have said that, given the essential mystery of the doctrine, the two kinds of conceptions need not be considered incompatible: the doctrine of the Trinity is a necessary consequence of Christology, and takes seriously the necessity for interrelation in the formation of all appearance or reality. The patristic concept of circumincessio (Gk., (em)perichoresis), the inner involvement of the Three Persons, anticipates the current social model of the Trinity, of three distinct realities, inseparably requiring each other to be the sort of reality they are, and therefore also only one reality.

the Trinity the three persons of the Christian Godhead; Father, Son, and Holy Spirit. The term is recorded from Middle English, and comes ultimately from Latin trinus ‘threefold’.
Trinity House a guild or fraternity originally established at Deptford, incorporated in the reign of Henry VIII, formerly having the official regulation of British shipping, and now chiefly concerned with the licensing of pilots and the erection and maintenance of lighthouses, buoys, and other aids to navigation, on the coasts of England and Wales.
Trinity Sunday the next Sunday after Pentecost, observed in the Western Christian Church as a feast in honour of the Holy Trinity.
Trinity term a session of the High Court beginning after Easter; (in some universities) the term beginning after Easter.