deep-rooted
adjective /ˌdiːp ˈruːtɪd/
  /ˌdiːp ˈruːtɪd/
[usually before noun]- very fixed and strong; difficult to change or to destroy
- a deep-rooted desire
 - The country’s political divisions are deep-rooted.
 - The custom of sending a greeting in a card had become a deep-rooted tradition.