The term JOINS ON can be defined as 'ABUTS', which is a five-letter word. ABUTS is a verb that means to be adjacent to or to border on something. It is often used in reference to land, such as two pieces of property that abut each other. ABUTS can also be used to describe two objects that are close together, but not necessarily touching. In this context, JOINS ON would mean that two objects are close together, but not necessarily touching.