TRANSEPT

The Transept is a  rectangular space inserted between the apse and nave in the early Christian basilica. It sprang from the need of procuring sufficient space for the increased number of clergy and for the proper celebration of the service. The bay at which the transept intersects the main body of the church is called the crossing. The transept itself is sometimes simply called the cross.The length of the rectangle either equals the entire breadth of the nave, , or it exceeds this breadth more or less, so that the transept extends beyond the walls of the nave. The transept generally terminates towards the north and south in a straight line.

Picture taken from: http://www.pitt.edu/~medart/menuglossary/transept.htm

Acknowledgement: http://www.newadvent.org/cathen/15018a.htm
                              http://www.britannica.com/EBchecked/topic/602515/transept

NAVE

The Nave is 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). The nave is that part of a church set apart for the laity, as distinguished from the chancel, choir, and presbytery, which are reserved for the choir and clergy. The separation of the two areas may be effected by screens or parapets, called cancelli. The term nave derives from the Latin navis, meaning “ship,” and it has been suggested that it may have been chosen to designate the main body of the building because the ship had been adopted as a symbol of the church.

Picture taken from : http://www.pitt.edu/~medart/menuglossary/nave.htm

Acknowledgement: http://www.britannica.com/EBchecked/topic/406945/nave

AISLE

The Aisle is a lateral or longitudinal divisions of a church, separated from the nave (sometimes called the centre aisle) by rows of piers, pillars, or columns. The term is popularly used to describe the passage between pews or seating. Sometimes a church has one side-aisle only. Often the aisle is continued around the apse. Occasionally the aisles stop at the transepts. The aisle is generally one story, but occasionally there is an upper story, sometimes used as a gallery. As a general rule, churches are divided into three aisles, but there is no fixed rule that governs the number.

Picture taken from : http://www.businessinsider.com/movement-to-tax-church-gains-momentum-2012-9

Acknowledgement: http://www.newadvent.org/cathen/01237c.htm