See electrocardiograph in American Heritage Dictionary 4
(ĭ-lĕkˌtrō-kärˈdē-ə-grăfˌ)
noun Abbr. EKG or ECG
An instrument used in the detection and diagnosis of heart abnormalities that measures electrical potentials on the body surface and generates a record of the electrical currents associated with heart muscle activity. Also called cardiograph.