Source : Webster's Revised Unabridged Dictionary (1913)

Diagrammatic \Di`a*gram*mat"ic\, a.
   Pertaining to, or of the nature of, a diagram; showing by
   diagram. -- {Di`a*gram*mat"ic*ly}, adv.

Source : WordNet®

diagrammatic
     adj : shown or represented by diagrams [syn: {diagrammatical}]