pro bono UK /prəʊ ˈbəʊnəʊ/US /proʊ ˈboʊnoʊ/ prepositional phrase1 •Without charging the usual fee; done voluntarily without fee, generally for clients or patients of limited means.The firm currently has about half a dozen pro bono cases at any one time.After he retired, he offered representation pro bono from time to time.