• Narthex: In architecture, a porch or vestibule of a church, generally colonnaded or arcaded and preceding the nave1.

• Nave: The central and principal part of a Christian church, extending from the entrance (the narthex) to the transepts (transverse aisle crossing the nave in front of the sanctuary in a cruciform church) or, in the absence of transepts, to the chancel (area around the altar)2.

• Aisles: A long, narrow space on either side of the nave of a church, usually between a row of columns or piers and the outer wall. It is often referred to as a side aisle1.

• Transept: An aisle between the apse and nave. It cuts across the nave and side aisles to form a cross-shaped (cruciform) floor plan1.

• Crossing: The space in a cruciform church formed by the intersection of the nave and the transept1.

• Ambulatory: A continuous aisle around a circular building, or a semi-circular aisle curving around the apse of a church behind the main altar. Developed during the Romanesque period, it made it easier for large religious processions to move about inside the church1.

• Porch: A porch in a church is a room-like structure at the church’s main entrance. It protects from the weather to some extent. Some porches have an outer door, others a simple gate, and in some cases, the outer opening is not closed in any way3.

• Towers: Towers are a common element of religious architecture worldwide and are generally viewed as attempts to reach skyward toward the heavens and the divine4. The interior of the dome or tower may be one of the major architectural features of the interior of the church5.

• Apse: The semicircular or polygonal recess at the end of a Christian church opposite the main entry, or in a wall of a Roman basilica. It was here that the altar was placed1.

• Chevet: The eastern end of a Gothic church, including choir, ambulatory, and radiating chapel1.

• Choir: The part of a church or cathedral where services are sung. It is usually east of the transept, and within the chancel, but may extend into the nave, and is often separated from the nave by a screen.1

Sources :

1: Church Architecture Flashcards | Quizlet.

2 : Nave | Gothic, Romanesque & Baroque Styles | Britannica

3 : Church porch - Wikipedia

4: Steeple - Wikipedia

5: Architecture of cathedrals and great churches - Wikipedia