narthex Syllabification: (nar·thex)Pronunciation: /ˈnärTHeks/Definition of narthex noun an antechamber, porch, or distinct area at the western entrance of some early Christian churches, separated off by a railing and used by catechumens, penitents, etc.. an antechamber or large porch in a modern church. Origin: late 17th century: via Latin from Greek narthēxnarthex in other Oxford dictionaries Definition of narthex in the British & World English dictionary