The term aisle, as an architectural term applying to churches, came from the Latin word ala, meaning a wing, that in its original sense meant the wing of a building or house. From this, the term is generally applied architecturally to areas added to the sides of large building, such as churches and cathedrals, and is illustrated in the side (aisle) areas of basilicas. In basilicas, aisles are usually separated from the central part of the building, the nave or other aisles, by colonnades or columns.
An early example is found in the basilica of Trajan that has a double set of aisles on either side of the nave. Other early examples include the original church of St. Peter in Rome and the basilica in Bethlehem. There are a number of churches with multiple aisles. These include St Sophia Cathedral in Kiev that has five aisles and the cathedral in Cordoba, Spain, which has nineteen.