ENTASIS, in architecture, the convex curve given to the taper of a column, spire or similar upright member, in order to avoid any appearance of hollowness or weakness. Entasis is almost uni versal in classic columns. It is exaggerated in Greek archaic Doric work, but grows more and more subtle during the 5th and 4th cen turies B.C. Many attempts have been made to find a mathematical basis for the entasis, and it has been reduced to all kinds of ellipti cal, hyperbolic, parabolic and even cycloidal curves. The immense variety of forms found indicates, probably, that the curve was laid out free-hand and purely empirically. Entasis is occasionally found in Gothic spires, and in the smaller Romanesque columns.