Definition of Petersen graph in US English:

Petersen graph

noun

Mathematics
  • A graph having ten vertices and fifteen lines, which may be drawn as a pentagram within a pentagon, each vertex of the latter being joined by a line to the nearest vertex of the former.

Origin

1940s; earliest use found in Proceedings of the Cambridge Philosophical Society. From the name of Julius Petersen, Danish mathematician, who devised it + graph, after German Petersensche Graph.