from The Century Dictionary and Cyclopedia
- n. In heraldry, a figure having eight lobes or eight subdivisions, like separate leaflets. It is used as the mark of cadency for the ninth son.
Above, far back in the clerestory arches, are octofoil windows with sills of over-lapping courses, which incline forward to the string course above the triforium.
The windows in the gable consist of two lesser windows, two-light, with quatrefoil heads, beneath a large octofoil, the whole grouped with blank panels at the side, beneath a cinquefoil moulding.