entasis

The entasis is almost invariably introduced in the spires of English churches.

The entasis of columns and curvature of what would ordinarily be straight lines is familiar to all students of architecture.

This is called the entasis of the spire, and belongs to the study of optics in architecture.

The shaft was covered with channelled flutings, and rose vertically with a convex extension of its circumference (called entasis).

The shaft is well shaped, with a moderate swelling (entasis).