I believe the correct
answer is a central open space within a church.
The nave (from “navis” meaning
“ship” in Latin) represent the central part of a Christian church, which sets apart
the laity, as distinguished from the chancel, choir, and presbytery, which are
reserved for the choir and clergy. This form of nave was firstly adapted by the
early Christian builders from the basilica Roman hall of justice. It was
lighted by a row of windows near the ceiling, called the clerestory, and the
main, central space was usually flanked on either side by one or two aisles. Other
examples of this kind of form of nave are Basilica of St. Peter’s and San Paolo
Fuori le Mura in Rome.