Mucus

n. fluid nasal secretion; viscous secretion of the membranes

Mucus is a slippery secretion of the lining of the mucous membranes in the body. It is a viscous colloid containing antiseptic enzymes (such as lysozyme) and immunoglobulins. Mucus is produced by goblet cells in the mucous membranes that cover the surfaces of the membranes. It is made up of mucins and inorganic salts suspended in water.  Phlegm is a type of mucus that is restricted to the respiratory tract, while the term mucus refers to secretions of the nasal passages as well.
See more at Wikipedia.org...

Mucus /mu·cus/ the free slime of the mucous membranes, composed of secretion of the glands, various salts, desquamated cells, and leukocytes. [more]Mucus - Community and Resources

Noun
1. protective secretion of the mucous membranes; in the gut it lubricates the passage of food and protects the epithelial cells; in the nose and throat and lungs it can make it difficult for bacteria to penetrate the body through the epithelium
(synonym) mucous secretion
(hypernym) secretion
(hyponym) phlegm, sputum
(substance-meronym) mucin

n. mucus, fluid nasal secretion; viscous secretion of the membranes