1.
If you are ~, you are very determined and do not give up easily.
He is regarded at the BBC as a ~ and persistent interviewer.
ADJ
~ly
In spite of his illness, he clung ~ly to his job.
ADV: usu ADV after v
2.
If you describe something such as an idea or belief as ~, you mean that it has a strong influence on people and is difficult to change or remove.
...a remarkably ~ belief that was to dominate future theories of military strategy.
= deep-seated
ADJ