A conceptual graph is a finite connected bipartite graph which consists of concepts and conceptual relations. Every conceptual relation has one or more arcs, each of which is linked to a concept. We define a multilevel conceptual graph to be a conceptual graph in which some of the concepts and conceptual relations arc sensitive.

p. 73 cited in: National Computer Security Conference Proceedings, 1992. DIANE Publishing Company. p. 320 - Conceptual Structures, 1984