1 Part of a church on either side of the nave or choir, divided from the latter by means of arcades, colonnades, or piers supporting the clerestorey. Aisles are commonly of less height than the nave, and the normal basilican form consists of a clerestoreyed nave with a lean-to aisle on each side, sometimes doubled so that there are two aisles on each side, but in England there are countless medieval churches with only one aisle. Transepts (called cross-aisles) may also have aisles to the liturgical east or west, but often have only an eastern aisle to accommodate chapels. In German hall-churches (Hallenkirchen) the aisles and nave are the same height, so there are no clerestoreys, but the aisle-windows are long and tall. Some churches are aisleless, i.e. are one main space, but buildings with aisles are called aisled. An aisle-gallery is one over the aisles, as in C18 London churches, usually necessitating windows under and over the galleries in the sidewalls.
2 Compartment of a timber-framed barn, hall, or house, defined by a row of posts separating it from the main body of the building.
3 Walk or passage in a theatre, church, or hall giving access to rows of seats.
4 Covered and enclosed burial-ground attached to a church.
5 Flanking wing of a building.