Voider 

Ermine  a mascle sa betw. two voiders gu

1. The flanch, flasque and voider are subordinaries, all formed by a segment of a circle taken out of the side or flank of the shield and are always borne in pairs, one on each side of the shield.

The flanch utilises the widest segment of the circle and thus exposes the least area of the field.

The flasque could be called a diminutive of the flanch, utilising a narrower segment of the circle and thus exposing a larger area of the field. The flasque is drawn square in Dutch heraldry.

The voider is the narrowest of the three, although some writers do not distinguish between the flasque and voider.

See Subordinary

2. In the suit of armour, the voider was a gusset of plate or mail which was used to cover the unprotected space between the elbow or knee joints.

See Armour