Heraldic shield

In heraldry, an escutcheon (/ᵻˈskʌtʃən/) is a shield that forms the main or focal element in an achievement of arms. The word is used in two related senses.

Firstly, as the shield on which a coat of arms is displayed. Escutcheon shapes are derived from actual shields used by knights in combat, and thus have varied and developed by region and by era. As this shape has been regarded as a war-like device appropriate to men only, British ladies customarily bear their arms upon a lozenge, or diamond-shape, while clergymen and ladies in continental Europe bear theirs on a cartouche, or oval. Other shapes are in use, such as the roundel commonly used for arms granted to Aboriginal Canadians by the Canadian Heraldic Authority.

Secondly, a shield can itself be a charge within a coat of arms. More often, a smaller shield is placed over the middle of the main shield (in pretence or en surtout) as a form of marshalling. In either case, the smaller shield is usually given the same shape as the main shield. When there is only one such shield, it is sometimes called an inescutcheon.

The word escutcheon is derived from Middle English escochon, from Anglo-Norman escuchon, from Vulgar Latin scūtiōn-, from Latin scūtum, "shield". From its use in heraldry, escutcheon can be a metaphor for a family's honour. The idiom "a blot on the escutcheon" is used to mean a stain on somebody's reputation.

...
Wikipedia