What is "spin foam"

n. (context physics English) A topological structure made out of two-dimensional faces that represents one of the configurations that must be summed to obtain a Feynman's path integral description of quantum gravity.

In physics, a spinfoam or spin foam is a topological structure made out of two-dimensional faces that represents one of the configurations that must be summed by functional integration to obtain a Feynman's path integral description of quantum gravity. It is closely related to loop quantum gravity.