persistent
adjectiveUK /pəˈsɪstənt/
US /pərˈsɪstənt/
Continuing to do something or exist even when it is difficult or takes a long time.
Her persistent knocking finally woke everyone in the house.
RELATED WORDS
OTHER MEANINGS
2. Continuing to exist or occur over a long period, especially something unwanted.
He suffered from a persistent cough for weeks.
3. Refusing to give up despite opposition or difficulty.
The persistent reporter kept asking questions until she got an answer.
4. Remaining in place or continuing without change.
A persistent smell of smoke lingered in the old cabin.