The term 'UNITE SECURELY' can be solved by the six-letter word 'CEMENT'. CEMENT is a binding material used to hold two or more objects together. It is made from a mixture of limestone, clay, and other materials that are heated and ground into a powder. CEMENT is often used in construction to create strong foundations and walls. It is also used to make mortar for laying bricks and tiles. CEMENT is an essential material for many building projects, as it provides a secure and lasting bond between two objects.