una·ry /ˈjunəri/
  (a.)一元的; 單元件的
  unary
  一目關係; 一元關係; 一元的; 一目的
  unary
  一一元
  unary
       adj : consisting of or involving a single element or component;
             "in a unary operation in a mathematical system one
             element is used to yield a single result"