Unite - if different people or organizations unite, or if something unites them, they join together in order to achieve something (come or bring together for a common purpose or action): -Our goal is to unite the opposition parties and defeat the President. (unite against/behind) - Party members united behind their leader. (unite to do something) - In 1960, the regions united to form the Somali Republic. Unify - if you unify two or more parts or things, or if they unify, they are combined to make a single unit (make or become united, uniform, or whole): - Strong support for the war has unified the nation. - His music unifies traditional and modern themes. (Longman, Oxford Dictionaries)