Noun
(initially) In Eastern Orthodoxy, the placement of a cross by a bishop which symbolises his approval of the construction of a church or monastery on the site the cross is placed.
(later) In Eastern Orthodoxy and Eastern Catholicism, an autonomous Orthodox church body (church, monastery, brotherhood, lavra, theological school) which does not answer to any local hierarch, but is ruled directly by the highest authority of the church, i.e. the primate of the said church (e.g. a Patriarch) or in the case of the Russian Orthodox Church between 1721 and 1918 by the Most Holy Synod. Similar to a personal prelature.
Source: en.wiktionary.org