per·fid·i·ous 
/pɚˈfɪdijəs/ adjective
/pɚˈfɪdijəs/ adjective [more perfidious; most perfidious] literary : not able to be trusted
▪ We were betrayed by a perfidious ally. : showing that someone cannot be trusted ▪ perfidious [=treacherous] acts
▪ We were betrayed by a perfidious ally. : showing that someone cannot be trusted ▪ perfidious [=treacherous] acts
