Englishtenacity
noun
the tenacity with which he stuck to his story:
persistence, pertinacity, determination, perseverance, doggedness, tenaciousness, single-mindedness, strength of will, firmness of purpose, strength of purpose, fixity of purpose, bulldog spirit, tirelessness, indefatigability, resolution, resoluteness, resolve, firmness, patience, purposefulness, staunchness, steadfastness, constancy, staying power, application, diligence, assiduity, sedulousness, insistence, relentlessness, inexorability, inexorableness, implacability, inflexibility;
stubbornness, intransigence, obstinacy, obduracy, obdurateness;
German Sitzfleisch;
informal stickability;
North American, informal stick-to-it-iveness;
rare continuance, perseveration.
▷antonyms irresolution, lack of resolve.
tenacity Oxford Dictionary of English