Dictionary of Algorithms, Data Structures, and Problems is a fine way of spending an idle hour. Just a sample below to whet your appetite:
minimum spanning tree (definition)

Definition: A minimum-weight tree in a weighted graph which contains all of the graph's vertices.

See also Kruskal's algorithm, Prim's algorithm, Steiner minimum tree, spanning tree.

Note: A minimum spanning tree is a near-optimal solution to the traveling salesman problem. First find the minimum spanning tree. Then convert the tree to a path by traversing the tree, say by depth first search.