Nosebleed: Bleeding from the blood vessels of the nose. The nose is rich in blood vessels and is situated in a vulnerable position on the face. As a result, any trauma to the face can cause bleeding, which may be profuse. Nosebleeds can also occur spontaneously when the nasal membranes dry out, crust, and crack, as is common in dry climates or during winter months, when the air is dry and warm from household heaters. People have increased susceptibility to nosebleeds if they are taking medications that prevent normal blood clotting, such as warfarin (brand name: Coumadin), aspirin, or any anti-inflammatory medication. Other predisposing factors include infection, trauma, allergic and nonallergic rhinitis, hypertension, alcohol abuse, and inherited bleeding problems. Also known as epistaxis.