Webster's Revised Unabridged Dictionary · 1913

Flanch

Flanch , noun

[Prov. English, a projection, Old French flanche flank. See Flank.]

1.
(Heraldry) A flange.
(Heraldry) A bearing consisting of a segment of a circle encroaching on the field from the side. [Rare]

Flanches are always in pairs. A pair of flanches is considered one of the subordinaries.