cas·ing 
/ˈkeɪsɪŋ/ noun
plural cas·ings /ˈkeɪsɪŋ/ noun [count] 1 : a layer on the outside of something that covers and protects it
▪ a sausage casing ▪ a casing for a shotgun shell 2 : a frame around a door or window
▪ a sausage casing ▪ a casing for a shotgun shell
