In heraldry, a flaunch (/flɔːntʃ/; also called flanches or flanks)[1] are among the ordinaries or subordinaries, consisting of two arcs of circles protruding into the field from the sides of the shield. The flaunch is never borne singly.
A very rare variation is square flaunches, as in the coat of Sheila-Marie Suzanne Cook and the coat of the US Coastguard Cutter Sequoia. Parker's glossary, s.v. Flaunches, cites two similar coats for Mosylton or Moselton with square flaunches.
Diminutive
While supposedly the diminutives of flaunches are flasques and voiders (which likewise cannot be borne singly), these exist only very rarely in modern heraldry, and in practice cannot be distinguished from flaunches. An example occurs in the coat of Liddell-Grainger of Ayton (second quarter for Liddell), "Argent fretty gules; two voiders or;..." (Scots Public Register, volume 38, page 3).
As a debruisement
Some early heraldic writers say that the illegitimate son of a noblewoman must bear her arms with "a surcoat"; that is, on (large) flaunches around a blank center.[1]