▪ (of a phone line) unavailable because already in use.British
▪ (of a lavatory) already in use.
2. having formally agreed to marry: "she was engaged to a lecturer"Similarbetrothedaffiancedpromised in marriageattachedinvolvedinformal:spoken forarchaic:plightedespousedOppositeunattached
3. (of a column) attached to or partly let into a wall.