This section is from the book "The American House Carpenter", by R. G. Hatfield. Also available from Amazon: The American House Carpenter.
309. - Mouldings: are so called because they are of the same determinate shape throughout their length, as though the whole had been cast in the same mould or form. The regular mouldings, as found in remains of classic architecture, are eight in number, and are known by the following names:
Fig. 183.
Annulet, band, cincture, fillet, listel or square.
Fig. 184,
Astragal or bead.

Fig. 185.
Torus or tore.

Fig. 186.
Scotia, trochilus or mouth.

Fig. 187.
Ovolo, quarter-round or echinus.

Fig. 188.
Cavetto, cove or hollow.

Fig. 189.
Cymatium, or cyma-recta.

Fig. 190.
Diverted cymatium, or cyma-reversa.
Some of the terms are derived thus: Fillet, from the French word fil, thread. Astragal, from astragalos, a bone of the heel - or the curvature of the heel. Bead, because this moulding, when properly carved, resembles a string of beads. Torus, or tore, the Greek for rope, which it resembles when on the base of a column. Scotia, from skotia, darkness, because of the strong shadow which its depth produces, and which is increased by the projection of the torus above it. Ovolo, from ovum, an egg, which this member resembles, when carved, as in the Ionic capital. Cavetto, from cavus, hollow. Cymatium, from kumaton, a wave.
 
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