A wing of a building, notably in a church separated from the nave proper by piers.

A clear path through rows of seating.

A clear corridor in a supermarket with shelves on both sides containing goods for sale.

Any path through an otherwise obstructed space.

(transport) Seat in public transport, such as a plane, train or bus, that's beside the aisle.

(US, politics) An idiomatic divide between the Republican Party and the Democratic Party, who are said to be on two sides of the aisle.

(by extension, metonymically) The path of a wedding procession in a church or other venue; marriage.