1. A subordinary in the form of a diamond-shaped bearing, having two obtuse and two acute angles. The lozenge is similar to the fusil but the latter is more elongated.
See Subordinary

Lozenge
fleury

Lozenge in point, in which the lozenge extends to all points of the shield; others call it four points.

Cross of four lozenges
Lozenges in cross.
Note: Lozenges may also be placed
in
bend, in
fess,
in pale and the like.
2. The form of the escutcheon upon which women, specifically spinsters and widows, place their Arms. As the shield used in war was peculiar to men, it was not considered appropriate for the female, hence an unmarried woman placed her Arms on a lozenge, perhaps in allusion to the fusil, or distaff. When married, she shares her husbands shield.