noun: A graph in which a series of connected straight lines connect points, each of which represents the value of a particular variable as a function of another variable.
noun: (graph theory) A graph L(G) which is derived from a given non-oriented graph G such that the vertices of L(G) represent edges of G and so that a clique in L(G) represents a common end-vertex shared by a set of represented edges. (A star subgraph in G transforms into a clique in L(G).)
noun: A graph which is the line graph (in the above sense) of some other graph.
