a long narrow passage (as in a cave or woods)
"The explorers huddled together to shield themselves from the wind as they crawled through the dark, damp aisle of the collapsing tunnel."
part of a church divided laterally from the nave proper by rows of pillars or columns
"The ancient stone aisle ran parallel to the main nave, separated only by a row of towering Romanesque columns."
A wing of a building, notably in a church separated from the nave proper by piers.
"During the cathedral service, the organist signaled to the choir standing in the narrow aisle between the stone piers."