pertinacious


pertinacious (http://definr.com/pertinacious)

     adj : stubbornly unyielding; "dogged persistence"; "dour
           determination"; "the most vocal and pertinacious of all
           the critics"; "a mind not gifted to discover truth but
           tenacious to hold it"- T.S.Eliot; "men tenacious of
           opinion" [syn: bulldog, dogged, dour, tenacious,
            unyielding]