Heraldry. A charge in the form of a lozenge, with a round hole in the middle through which the field appears.
Origin
Mid 17th century; earliest use found in George Havers (fl. 1665). From French †rustre, alteration of Middle French, French ruste, itself an alteration of Middle French rute from Middle Dutch rute rhombus (also in specific heraldic use; Dutch ruit), of uncertain origin, perhaps an extended use of the plant name rute, on account of the pattern formed by the tips of its petals.