ousia
Noun
Meaning
(theology) The essential nature or ‘substance’ of God, often as contrasted to the ‘energies’ (external actions and influences) through which he is manifest.
(philosophy) Essence, being.
Source: en.wiktionary.orgExamples
The Father is the eternal, infinite and uncreated reality, that the Christ and the Holy Spirit are also eternal, infinite and uncreated, in that their origin is not in the ousia of God, but that their origin is in the hypostasis of God called the Father.
Theory The most natural epithets of Thales are " materialist " and " naturalist ", which are based on ousia and physis.
The etymology of the Greek word parousia is related to para "beside" ousia "presence".
Substance, potentiality and actuality seeAlso Aristotle examines the concepts of substance and essence (ousia) in his Metaphysics (Book VII), and he concludes that a particular substance is a combination of both matter and form.