The side, or flank (Fr. flanc), is a heraldic ordinary resembling a pale that has been displaced () to either the dexter or sinister edge of the field. Pierre-Barthélemy Gheusi, following M. Aug. Tailhades, groups the sides (flanc dextre and flanc sénestre) with the chief and base (and bordure) as ordinaries (pièces honorables) that are affixed to an edge of the field by their longest side.
The use of the term side to refer to the ordinary (or division of the field) is not to be confused with the use of the term to refer to regions or edges of the field or points of an escutcheonâÂÂthe dexter and sinister sides or points flanc dextre and flanc sénestre. In English, sides as charges are typically referred to as âÂÂsides sinisterâ or âÂÂsides dexterâÂÂ, in contradistinction to the âÂÂsinister sideâ and âÂÂdexter sideâ as edges or portions of the field.
In some heraldic traditions, such as the English, it is specified that the side extend not more than one-sixth of the width of the field; in others, such as the , it may extend to up to one-third the width of the field.
Like other heraldic ordinariesâÂÂsuch as the pale, fess, chief, bend, base, or pileâÂÂthe side is possessed of a fundamental : it can be conceived as alternately a charge or as a division of the field. As with any principal charge, the side can bear another charge or a group of charges. Its edge can also be modified by variations of line. It can be modified by variations of the field as well.