in Geometry, a spiral line. The word is Greek, ἑλίξ, and literally signifies a wreath or winding, from ἕλεος, involco. In architecture, some authors make a difference between the helix and the spiral. A staircase, according to Daviler, is in a helix, or is helical, when the stairs or steps wind round a cylindrical newel; whereas the spiral winds round a cone, and is continually approaching nearer and nearer its axis.

HELIX is also applied, in Architecture, to the caulicles or little volutes under the flowers of the Corinthian capital, which are called urillae.