a to-and-fro grating, rasping, or, rarely, creaking sound heard over the heart in some cases of pericarditis, due to rubbing of the inflamed pericardial surfaces as the heart contracts and relaxes; during normal sinus rhythm it is usually triphasic; during any rhythm it may be biphasic or uniphasic. SYN: pericardial rub, pericardial friction rub.
