The term JOINS FIRMLY can be solved by two crossword solutions, GLUES (5 letters) and CEMENTS (7 letters). GLUES are substances that are used to stick two or more objects together. They are usually made of a sticky material such as rubber, resin, or adhesive. CEMENTS are materials that are used to bind two or more objects together. They are usually made of a hard material such as concrete, mortar, or plaster. Both GLUES and CEMENTS are used to firmly join two or more objects together.