noun. A portico or lobby of an early Christian or Byzantine church or basilica, originally separated from the nave by a railing or screen.

noun. An entrance hall leading to the nave of a church.

noun. A western vestibule leading to the nave in some (especially Orthodox) Christian churches.

"A narthex is not a gathering space or overflow social hall; it is a place of transition from world outside to the heavenly reality within."

endonarthex  exonarthex