Bowtell

Bowtell - upwardly expanding curved surface found beneath the abacus - rectangle found on top of column, labelled number 1.

Bowtell is derived from the medieval term bottle;^[1] in architecture it refers to a round or corniced molding below the abacus in a Tuscan or Roman Doric capital; the word is a variant of boltel, which is probably the diminutive of bolt, the shaft of an arrow or javelin. A roving bowtell is one which passes up the side of a bench end and round a finial, the term roving being applied to that which follows the line of a curve.^[2]

Notes

1. Treatise on architecture:..., ed. Arthur Ashpitel, p. 94, (Edinburgh 1867). A round molding can also be referred to as a torus.
2.  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Bowtell". Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 349.