Benny, I believe that Lex is referring to seing where two seperate meshes intersect, not one mesh with non-manifold geometry.

Lex - I don't know of any functions right off that do what you're looking for. In theory, you could use 'Mesh->Booleans->Intersection' to give you some idea of which parts of two meshes are intersecting, but that's a little more cumbersome than what it sounds like you want - and there's a couple of downsides to using that method, as well (like having to worry about non-manifold geometry).
As for the term you're looking for, I think I'd be looking for something with 'intersecting geometry'. So you weren't too far off.