The number of regular recurrences of an event during a given period of time. Examples in medicine are the heartbeat, and sound vibrations in the EAR or vocal cords.
The word is also used to describe frequent passage of urine, a symptom that is usually caused by disorders in the urinary tract – for example, an infection; or any systemic disease which increases the daily output of urine – for example, DIABETES MELLITUS and diabetes insipidus, or disorders of the kidney.