English mathematician and engraver. A skillful and exuberant calligrapher, Cocker also taught writing and arithmetic. He wrote a number of works that bore his name, such as Cocker's Urania and Cocker's Morals. His most famous work was Cocker's Arithmetic, which ran to more than 100 editions over a period of 100 years. However, some sources suggest that Cocker's editor and publisher forged the book. The phrase "according to Cocker," meaning absolutely correct, was common usage for many years.