Mucus is a thick, slippery substance produced by the mucous membranes in various parts of the body, including the respiratory and digestive systems. It plays an important role in keeping these areas moist, protecting them from irritants, pathogens, and physical damage. Mucus helps trap dust, pollen, and bacteria, making it easier for the body to expel them.
The word "mucus" comes from the Latin word "mucus," which means "slime." The term has been used in English since the 14th century.