1 : 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"
3 : marked by care and persistent effort; "her assiduous attempts to learn French"; "assiduous research"; "sedulous pursuit of legal and moral principles"
