Cusps

Chambers's Encyclopaedia, Volume 3: Catarrh to Dion, p. 626

Cusps, curved projections or featherings in Gothic tracery, arches, panels, &c. They began in the Early English period, when they projected from the flat soffit of the arch; but they were soon comprised in the mouldings, and generally spring from the inner splay or cavetto. In Decorated and Perpendicular work the points were lengthened, and were frequently ornamented with flowers, heads, &c.

A detailed illustration of a Gothic cusp, showing a curved, pointed projection with intricate floral and scrollwork ornamentation.
A detailed illustration of a Gothic cusp, showing a curved, pointed projection with intricate floral and scrollwork ornamentation.
Source scan(s): p. 0637