(mathematics) A graph with some edges drawn as double or triple lines, arising in the classification of semisimple Lie algebras over algebraically closed fields, in the classification of Weyl groups and other finite reflection groups, and in other contexts.

plural of Dynkin diagram

plural of Coxeter-Dynkin diagram

(geometry, algebra) A graph with numerically labelled edges (called branches) representing the spatial relations between a collection of mirrors (or reflecting hyperplanes).