from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A portico or lobby of an early Christian or Byzantine church or basilica, originally separated from the nave by a railing or screen.
- n. An entrance hall leading to the nave of a church.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A western vestibule leading to the nave in some (especially Orthodox) Christian churches.
Late Greek narthēx, from Greek, box, giant fennel, perhaps of Indic origin.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek νάρθηξ (narthēks, "giant fennel"), later ‘casket’ (modern Greek νάρθηκας). (Wiktionary)