church architecture

Apse
In architecture, the apse (Greek ἀψίς (apsis), then Latin absis: "arch, vault"; sometimes written apsis; plural apses) is a semicircular recess covered with a hemispherical vault or semi-dome.  In Romanesque, Byzantine and Gothic Christian abbey, cathedral and church architecture, the term is applied to a semi-circular or polygonal termination of the main building at the liturgical east end (where the altar is), regardless of the shape of the roof, which may be flat, sloping, domed or hemispherical.

The apse is the semicircular or polygonal termination to the choir or aisles of a church. In relation to church architecture it is generally the name given to where the altar is placed or where the clergy are seated.

Nave
In Romanesque and Gothic Christian abbey, cathedral basilica and church architecture, the nave is the central approach to the high altar, the main body of the church.  "Nave" (Medieval Latin navis, "ship") was probably suggested by the keel shape of its vaulting.  The nave of a church, whether Romanesque, Gothic or Classical, extends from the entry -- which may have a separate vestibule, the narthex -- to the chancel and is flanked by lower aisles separated from the nave by an arcade.  If the aisles are high and of a width comparable to the central nave, the structure is sometimes said to have three naves.

Transept
A transept (with two semitransepts) is a transverse section, of any building, which lies across the main body of the building.  In Christian churches, a transept is an area set crosswise to the nave in a cruciform ("cross-shaped") building in a Romanesque and Gothic Christian church architecture.  Each half of a transept is known as a semitransept.

The transept of a church separates the nave from the sanctuary, whether apse, choir, chevet, presbytery, or chancel.  The transepts cross the nave at the crossing, which belongs equally to the main nave axis and to the transept.  Upon its four piers, the crossing may support a spire (e.g., Salisbury Cathedral), a central tower (e.g., Gloucester Cathedral) or a crossing dome (e.g., Saint Paul's Cathedral).

Narthex
The narthex of a church is the entrance or lobby area, located at the end of the nave, at the far end from the church's main altar.  Traditionally the narthex was part of the church building, but it was not considered part of the church proper.  It is either an indoor area separated from the nave by a screen or rail, or an external structure such as a porch.

Chancel
The chancel (or presbytery) is the space around the altar in the sanctuary at the liturgical east end of a traditional Christian church building, possibly including the choir. It may terminate in an apse.

As well as the altar, the chancel usually houses the credence table and seats for officiating and assisting ministers. In Anglican and Methodist churches it will usually include the choir. In some traditions, the pulpit and lectern may be in the chancel, but in others these functions are considered proper to the nave.


The chancel is typically raised somewhat above the level of the nave, where the congregation gathers. It may be separated from the nave by a rood screen, a rail, or an open space. In some churches, the congregation may gather on three sides or in a semicircle around the chancel.

Sources:

http://en.wikipedia.org/wiki/Apse
http://en.wikipedia.org/wiki/Nave
http://en.wikipedia.org/wiki/Transept
http://en.wikipedia.org/wiki/Narthex
http://en.wikipedia.org/wiki/Chancel