(often misspelled as pathognomic and sometimes as pathomnemonic) is a term, often used in medicine, that means characteristic for a particular disease. A pathognomonic sign is a particular sign whose presence means that a particular disease is present beyond any doubt. Labelling a sign or symptom "pathognomonic" represents a marked intensification of a "diagnostic" sign or symptom.
The word is an adjective of Greek origin (παθογνωμονικόν [σύμπτωμα]), derived from páthos ("πάθος" meaning "disease") and gnōmon ("γνώμον" meaning "judge").