The most common meaning of thickness is a length measuring the distance between opposite surfaces of a three-dimensional object. Depending on orientation and convention, this dimension may be called the object's depth, breadth, or height.
The term is also used for several graph invariants. The graph thickness of a graph is the minimum number of planar subgraphs whose union is the graph. The book thickness is the minimum number of pages in a book embedding, while interval thickness is another name for pathwidth.
