The UKRAINIAN GREEK CATHOLIC CHURCH (UGCC) is the largest of the Eastern Catholic Churches sui juris.

The UGCC is a Church of the Byzantine rite which is in full ecclesial communion with the Pope of Rome and acknowledges his spiritual and jurisdictional authority. In this context "rite" means liturgical, theological, spiritual and canonical tradition.

OTHER NAMES FOR THIS CHURCH: Uniate Church; Greek Catholic Church; Greco-Catholic Church; Ukrainian Catholic Church; Ukrainian Catholic Church of the Byzantine rite; Kyivan Catholic Church.

The name Greek Catholic Church was introduced by the Empress Maria-Teresa in 1774 to distinguish this Church from the Roman Catholic and Armenian Catholic Churches.
In official church documents the term Ecclesia Ruthena unita was used. In 1960 the name Ukrainian Catholic Church started to be used in official documents to refer to Ukrainian Catholics in the diaspora and the underground Church in Soviet Ukraine. In the papal statistical annual Annuario Pontificio the name Ukrainian Catholic Church of the Byzantine rite is used. At the Synod of Bishops of the UGCC (September 1999) the name Kyivan Catholic Church was proposed, to emphasize the identity of this Church.

(from http://www.ugcc.org.ua/eng)