entasis

Convex curve given to a column, spire, or similar upright member to avoid the optical illusion of hollowness or weakness that would arise from normal tapering. Exaggerated in Greek work of the Doric order, it grew more and more subtle in the 5th–4th century BC. Entasis is also occasionally found in Gothic spires and in smaller Romanesque columns.

Find more information on entasis. Upgrade to Britannica Online for more on entasis.