Trinitarian theology has long had its own technical vocabulary, comprised of special words used to speak about trinitarian ideas, as well as everyday words with special nuances and significance in trinitarian discussion. Since not being familiar with what these words mean, or how someone else is using them, can be very confusing, I’ve set out to briefly define some important terms below. Part of the debate over different articulations of the doctrine of the Trinity pertains to how these terms are understood, so these definitions will not be universally agreed upon; my goal is to clearly set forth how I use them and understand them, so that people can have a clear idea of what I mean when I use the terms.
beget: to cause to exist directly from one’s self. Used specially of the Son of God in reference to His unique and direct generation from the Father.
being: entity, of which there are two kinds: generic being, and individual being. Generic being is a nature; individual (or numeric) being is a particular concretely existing entity. Synonyms for being: substance, essence, ousia; these can be used in either a generic or individual sense, as the term ‘being’ can. Synonyms for ‘generic being’: nature, universal. Synonyms for individual being (or numerical being): hypostasis, person, particular.
consubstantial: of the same substance. Because substance can carry either a generic or individual meaning, so can this term as well. If meant generically, then it indicates that two distinct individual beings have the same generic being; such as, that two persons have the same nature. If meant numerically, it means that two persons are one individual being, or person.
create: to bring into existence, or to cause. In this sense only the Father is uncreated, as He alone is uncaused, and the Son and Spirit may be called creatures. In this sense the ante-nicene orthodox fathers, and Homoians following them, used the term.
deity: the dominion of a god; synonyms include godhood/godhead, and divinity.
essence: being, or substance (Greek term ‘ousia’). Subject to a generic or an individual meaning, see ‘being’ above.
god: a person or item in possession of dominion; so the term is used in the scriptures in reference to the Father, the one God, on account of His supreme dominion over all; in reference to the Son of God, on account of His sharing in His Father’s dominion over the universe, while Himself being subject to the Father as His God; and in reference even to angels, satan, and men, in respect to the relative dominion and authority they have. As Sir Isaac Newton said, “a true, supreme, or imaginary dominion makes a true, supreme, or imaginary God.”.
hypostasis: an individual being; in the case of a rational subject, a person. This term has been used since at least the time of Origen to distinguish Father, Son, and Spirit from one another, as three hypostases.
infinite: to be without any external limitation of bound
nature: a set of definitive communicable ontological properties. For example, human nature is the collection of all properties which define what it is to be human, and are passed on from parent to child.
ousia: the Greek term for being, also translated as ‘substance’ and ‘essence’. Admits of a generic and numerical usage, see ‘being’ above. It is noteworthy that prior to the ante-nicene era, the generic usage of the term was not a synonym for nature, as it has come to mean in the nicene era and since, but the ‘stuff’ or ‘material’ that an individual is composed of.
particular: an individual being; synonymous with hypostasis and individual being, and with person, in the case of a rational subject.
person: a rational individual being. So the term is used of men, angels, and persons of the Trinity. Synonym to hypostasis.
substance: being; can be used in either a generic or individual/numerical sense, see ‘being’ above. Synonyms include: being, essence, ousia.
Supreme Being: a term or title used to refer to that one individual Being which alone is the supreme uncaused Cause of all else that exists, and which has absolute supreme authority and dominion over all things which He has caused; the one God.
universal: a nature, or generic being. Synonyms include nature, and ousia, essence, substance, and being, used in their generic, rather than individual, sense.