The term "head-rail" can have a few different synonyms depending on the context. If referring to a horizontal structural member at the top of a fence or railing, it could be called a "top-rail" or "cap-rail." If referring to a rail attached to the headboard of a bed, it could be called a "headboard-rail" or a "bed-rail." In the context of a boat, a "head-rail" could also be referred to as a "bow-rail" or "pulpit." Regardless of the specific terminology used, all of these components serve as a protective barrier and act as a support for the structure they are attached to.