I'm not sure what you mean but I think you mean:
- What is the Hypostatic Union?
If this is not what you meant, I have no idea what you are talking about. Those words are not even on Wikipedia or the web. If needed, check the spelling of the word with a friend and re-ask your question.
From the New Advent web site: Hypostatic Union
A theological term used with reference to the Incarnation to express the revealed truth that in Christ one person subsists in two natures, the Divine and the human. Hypostasis means, literally, that which lies beneath as basis or foundation.
So although Jesus is one Person in the Trinity, that Man - Jesus, has two natures: a divine nature and a human nature, neither of which conflicted with each other. This is a mystery of faith that we can partially understand by reason but not completely, at least on earth.
Although the Catechism of the Catholic Church doesn't use the word: Hypostatic Union, it does say this:
The formation of the Trinitarian dogma
249 From the beginning, the revealed truth of the Holy Trinity has been at the very root of the Church's living faith, principally by means of Baptism. It finds its expression in the rule of baptismal faith, formulated in the preaching, catechesis and prayer of the Church. Such formulations are already found in the apostolic writings, such as this salutation taken up in the Eucharistic liturgy:
"The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all."
(2 Corinthians 13:13; cf. 1 Corinthians 12:4-6; Ephesians 4:4-6)
250 During the first centuries the Church sought to clarify her Trinitarian faith, both to deepen her own understanding of the faith and to defend it against the errors that were deforming it. This clarification was the work of the early councils, aided by the theological work of the Church Fathers and sustained by the Christian people's sense of the faith.
251 In order to articulate the dogma of the Trinity, the Church had to develop her own terminology with the help of certain notions of philosophical origin: substance, person or hypostasis, relation and so on. In doing this, she did not submit the faith to human wisdom, but gave a new and unprecedented meaning to these terms, which from then on would be used to signify an ineffable mystery, "infinitely beyond all that we can humanly understand". (Pope Paul VI, Solemn Profession of faith: Credo of the People of God § 2)
252 The Church uses:
- the term substance (rendered also at times by essence or nature) to designate the divine being in its unity
- the term person or hypostasis to designate the Father, Son and Holy Spirit in the real distinction among them, and
- the term relation to designate the fact that their distinction lies in the relationship of each to the others.
In the early Church there were many heresies or incorrect teachings about who Jesus was.
You may find my Early Christian heresies page (temporarily off-line) interesting.
I hope this helps,