This is called the 'transept' and its purpose is to provide separation between the Sanctuary and the Nave. Sometimes the transept will include an area for the choir (although a loft is more common) and/or statuary, or side altars.
The name for the aisle that crosses the nave is called the transept. It typically intersects the nave at a right angle, creating a cross-shaped floor plan in churches with a cruciform layout.
The Nave is the middle part of the Church. This is where the congregation sits during the service, and is flanked by aisles on each side.
If there is only one room, then it is just called "the chapel", if it is divided, the sanctuary is where the altar is, and the nave would be outside the sanctuary where there would be pews, etc. If there is an anteroom, it is called a narthex.
Nave
It isn't called anything. It is just called part of the nave.
It is called the cruciform. It is the combined shapes of the nave and transepts.
A nave
Usually the walkway in Anglican Church would be known as the nave
Nave is not an adjective. It is a noun for the middle part of a church.
The central part of a church is called an altar. This is a sacred part of the church and the place from which the sermons are preached.
A long rectangular room in a Christian church during the early Middle Ages was called a "nave." The nave was the central part of the church where the congregation would gather for worship. It typically featured a high ceiling and was often flanked by aisles, leading to the altar at the front of the church. The design of the nave played a crucial role in the overall layout and functionality of early medieval churches.
If you mean the side arms of a church, it is called "the transept". Each of the two may contain a chapel.