Strongback is a term used to describe a variety of items, including a type of spinal support device and a type of wooden beam used in construction. Synonyms for strongback include backbone, spine, support, brace, and reinforcement. Backbone and spine both refer to the structure of the human body and can be used to describe something that provides strength and support. Support and brace are more general terms that can be used to describe any type of supportive device, while reinforcement specifically refers to something that strengthens a structure or material. Overall, there are several different words that can be used as synonyms for strongback, depending on the context in which the term is being used.