persistent Synonyms

tenacious dogged unyielding relentless unrelenting continuing staying pertinacious persevering steadfast lasting incessant durable resolute stubborn indefatigable enduring determined tight sustained substantial subacute sustainable timeless unremitting unflinching unfailing undying undaunted tireless unconquerable unbroken tough tolerant stiff strong-minded strong single-minded settled sequential sempiternal sedulous scrappy robust rigid reverberatory sound stable static stout