A shape-describing predicate (q.v.) and restricted specialization (see Genl Preds WRT Types) of Isa that relates a spatial object to a collection of things having (at least approximately) the same shape (see configuration). (shape OBJECT SHAPETYPE) means that SHAPETYPE characterizes OBJECT's shape (at some level of generality). If SHAPETYPE is a collection of things all having the same dimensionality as OBJECT (see spatial thing type by number of dimensions), OBJECT might actually be an instance of SHAPETYPE; but if SHAPETYPE is a collection of things all having the a different dimensionality than OBJECT, OBJECT can only approximate the shape in question.

For example, (shape MyCrystalBall sphere) holds because my crystal ball is a solid sphere. On the other hand (shape MyMousePad rectangle), while true, only means that my mouse pad is roughly rectangular in shape, as a three-dimensional object like a mousepad can't literally have a two-dimensional shape.

When making a ground-atomic assertion to the Knowledge Base regarding a particular object's shape it is normally advisable to use the most specific applicable configuration available. But note that the predicate shape itself implies no such thing; a more-inclusive shape-type will always characterize an object whenever a (correlatively) less-inclusive shape-type does. Thus, (shape MyMousePad polygon) holds if the second example above does.

See also the nearly corresponding type-level function Common Shape Fn.