an ‧ tith ‧ e ‧ sis /ænˈtɪθəsəs, ænˈtɪθɪsəs/ BrE AmE noun ( plural antitheses /-siːz/) [countable]
[ Date: 1500-1600 ; Language: Late Latin ; Origin: Greek , 'opposition' , from antitithenai 'to be against' , from anti- ( ⇨ ↑ anti- ) + tithenai 'to put' ]
formal the complete opposite of something
antithesis of
This is not democratic. It is the antithesis of democracy.