mucous layer
/ˌmjuːkəs ˈleɪə/noun
1 Anatomy. A mucosal layer, a mucous membrane. Now rare.
2 Histology. The deep layer of a stratified squamous epithelium, comprised of living cells. Compare Malpighian layer, rete mucosum. Now historical.
3 Biology. A layer of mucus, especially that overlying a mucous membrane.
Origin
Mid 19th century (in an earlier sense). From mucous + layer.