1 (of a person) very determined to do something and not willing to give up easily: The president is keeping a tenacious grip on power.
az: əzmkar, inadkar
ru: упорный, настойчивый
2 (of a belief, habit, illness etc) to continue to exist or be influential for a long time: Friends of ex-smokers can support them emotionally and play an important role in helping them beat a tenacious habit.
az: güclü, inadkar
ru: сильный, прочный