Source : Webster's Revised Unabridged Dictionary (1913)

Pathognomonic \Pa*thog`no*mon"ic\, a. [Gr. ? skilled in judging
   of diseases; ? a disease + ? skilled: cf. F. pathognomonique.
   See {Gnomic}.] (Med.)
   Specially or decisively characteristic of a disease;
   indicating with certainty a disease; as, a pathognomonic
   symptom.

         The true pathognomonic sign of love jealousy.
                                                  --Arbuthnot.