ENTASIS

in architecture, the 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. Entasis is almost universal in Classic columns. Exaggerated in Greek archaic Doric work, it grew more and more subtle in the 5th and 4th centuries BC. (Entasis is also occasionally found in Gothic spires and in the smaller Romanesque columns.) In the many attempts that have been made to find a mathematical basis for the entasis, it has been reduced to all kinds of elliptical hyperbolic, parabolic, and even cycloidal curves. The immense variety of forms indicates, however, that the curve was probably laid out freehand and purely empirically.