What is the medical definition of runny nose?

The medical term for a runny nose is rhinorrhea. It is a condition characterized by the excessive production and discharge of mucus from the nose. Rhinorrhea can be caused by a variety of factors, including allergies, colds, flu, sinusitis, and other respiratory infections. It can also be a symptom of more serious conditions, such as a deviated septum or nasal polyps. Treatment for rhinorrhea typically involves addressing the underlying cause. In some cases, over-the-counter medications, such as decongestants or antihistamines, may be used to relieve symptoms.