mucus: protective secretion of the mucus 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
secretion: a functionally specialized substance (especially one that is not a waste) released from a gland or cell
ginkgopsida: ginkgos: in some systems classified as a class and in others as a subdivision; used in some classifications for one of five subdivisions of Gymnospermophyta