Definition (Adjective) Of things, qualities, conditions, etc.: that once was or existed; former, erstwhile. In Context "For over a century, the formerly Portuguese colony of Macao has been much overshadowed by its neighbor, the quondam British colony of Hong Kong, always far larger in both area and population." Michael Share, Where Empires Collided: Russian and Soviet Relations with Hong Kong, Taiwan, and Macao, 2007.