A subcollection of spatial thing. Each instance of geometric form is a spatially-connected spatial thing (of one, two, three, or four dimensions) that either (i) has or approximates a simple geometric shape (e.g. it is a space line or a hemisphere) or (ii) consists of a small number of parts in a relatively simple (and stable) simple geometric configuration, where each such part has or approximates a simple geometric shape (e.g. a table consisting of a 3-D-disc-shaped top and four cylindrical legs). A geometrically-describable thing might be tangible or intangible.
Note that what counts as approximating a given simple geometric shape -- and thus what spatial things count as GeometricallyDescribableThings -- varies with context. In a context that was so fine-grained shape-wise that even the shapes of the individual molecules on the surface of an object were considered relevant to the object's shape, perhaps nearly every (connected, solid) tangible object would be geometrically-describable. In more everyday contexts, on the other hand, an unopened can of soup would be geometrically-describable (as a cylinder), while a telephone or an animal's body would probably not.
Note that what counts as approximating a given simple geometric shape -- and thus what spatial things count as GeometricallyDescribableThings -- varies with context. In a context that was so fine-grained shape-wise that even the shapes of the individual molecules on the surface of an object were considered relevant to the object's shape, perhaps nearly every (connected, solid) tangible object would be geometrically-describable. In more everyday contexts, on the other hand, an unopened can of soup would be geometrically-describable (as a cylinder), while a telephone or an animal's body would probably not.