Final answer:
The central space or aisle in a Romanesque or Gothic cathedral is called the nave, a term derived from the resemblance of a cathedral's ceiling to the inverted hull of a ship.
Step-by-step explanation:
The large central space or aisle in a Romanesque or Gothic cathedral is called the nave. This term originates from the Latin word for ship as the rafters of a cathedral's ceiling resemble the ribs of an inverted ship's hull. The nave is the main body of the church where congregants gather and is flanked by aisles on each side. It extends from the main entrance to the apse, which is the semicircular or polygonal termination of the choir or chancel. The nave is typically taller than the surrounding aisles, creating a clerestory that allows light to flood the interior. Such design is intentional to maintain a longitudinal plan, aligned with the central axis which culminates at the altar. In contrast to eastern churches that often have a central plan, such as the Church of San Vitale in Ravenna, Romanesque and Gothic cathedrals adopted the basilica style to reflect Christian symbolism and functional considerations.