Meaning of “ingrained” - Learner’s Dictionary

ingrained

adjective uk us /ɪnˈɡreɪnd/
BELIEFS

Ingrained beliefs, behaviour, problems, etc have existed for a long time and are difficult to change:

For most of us, watching television is a deeply ingrained habit.
DIRT

Ingrained dirt has got under the surface of something and is difficult to remove.

(Definition of “ingrained” from the Cambridge Learner’s Dictionary © Cambridge University Press)