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
something or someone that causes trouble; a source of unhappiness; "washing dishes was a nuisance before we got a dish washer"; "a bit of a bother"; "he's not a friend, he's an infliction"