The term 'firmly attached' can be described by four different crossword solutions: FAST (4 letters), AFFIXED (7 letters), bonded (6 letters), and CEMENTED (8 letters). FAST means to move quickly, AFFIXED means to attach or stick something in place, bonded means to join two things together, and CEMENTED means to make something permanent. All of these words describe the concept of firmly attaching something, whether it is done quickly, with an adhesive, through a bond, or with cement.