1. In soft deformation, the point at which a deformation falls off to zero. Defined in terms of a falloff radius.

2. In Fluid Effects, a region that gives shape to fluid substances, used for example to keep a cloud within a certain shape or to define the rough shape of an explosion. Specify a falloff region by painting it or using a curve in a container. The edge of the falloff area is soft (because there are no collisions), and there is no buildup of density in the area.